feat(client): 添加 Python 客户端及示例应用

- 新增 python-client 模块，提供 ConfigClient 配置拉取、定时同步、变更监听
- 使用 pyaes 替代 cryptography 实现 AES 解密，避免编译问题
- 新增 python-client-demo Flask 示例应用
- .gitignore 添加 Python 相关忽略规则

python-client/README.md

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+# Kenaito Config Center Python Client
+
+## 安装
+
+```bash
+cd python-client
+pip3 install -e .
+```
+
+## 快速开始
+
+```python
+from kenaito_conf import Config, ConfigClient
+
+config = Config(
+    base_url="http://localhost:8080",
+    app_name="my-app",
+    env="daily",
+    sync_interval=30,
+)
+
+client = ConfigClient(config)
+
+# 监听配置变更
+def on_change(changed):
+    for k, v in changed.items():
+        print(f"config changed: {k} = {v}")
+
+client.on_change(on_change)
+
+# 启动客户端（拉取配置 + 开启定时同步）
+client.start()
+
+# 获取配置
+value = client.get("database.host")
+all_configs = client.get_all()
+
+# 停止
+client.stop()
+```
+
+## 配置项
+
+| 参数 | 说明 | 默认值 |
+|------|------|--------|
+| `base_url` | 配置中心地址 | 必填 |
+| `app_name` | 应用名称 | 必填 |
+| `env` | 环境（dev/daily/prod） | `dev` |
+| `version` | 配置版本 | `latest` |
+| `token` | 认证令牌 | 空 |
+| `sync_interval` | 同步间隔（秒） | `60` |
+| `ignore_global` | 是否忽略全局配置 | `False` |
+| `cache_dir` | 本地缓存目录 | `.` |
+
+## Demo
+
+```bash
+cd python-client-demo
+pip3 install -r requirements.txt
+python3 app.py
+```
+
+Demo 默认监听 `8082` 端口，访问 `http://localhost:8082/` 查看配置。
+
+环境变量覆盖：
+
+| 环境变量 | 说明 | 默认值 |
+|----------|------|--------|
+| `SERVER_PORT` | 服务端口 | `8082` |
+| `KENAITO_BASE_URL` | 配置中心地址 | `http://localhost:8080` |
+| `KENAITO_APP_NAME` | 应用名称 | `kenaito-springboot-demo` |
+| `KENAITO_PROFILE` | 环境 | `daily` |
+| `KENAITO_VERSION` | 配置版本 | `latest` |
+| `KENAITO_TOKEN` | 认证令牌 | 空 |
+| `KENAITO_SYNC_INTERVAL` | 同步间隔（秒） | `30` |
+| `KENAITO_CACHE_DIR` | 缓存目录 | `.` |

python-client/kenaito_conf/__init__.py

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+from kenaito_conf.client import ConfigClient
+from kenaito_conf.config import Config
+
+__all__ = ["ConfigClient", "Config"]
+__version__ = "1.0.0"

python-client/kenaito_conf/cache.py

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+import json
+import os
+
+CACHE_FILE = "config-cache.json"
+
+
+class Cache:
+    def __init__(self, cache_dir: str = "."):
+        self.cache_dir = cache_dir
+
+    def write(self, data: dict) -> None:
+        path = os.path.join(self.cache_dir, CACHE_FILE)
+        with open(path, "w", encoding="utf-8") as f:
+            json.dump(data, f, ensure_ascii=False)
+
+    def read(self) -> dict | None:
+        path = os.path.join(self.cache_dir, CACHE_FILE)
+        try:
+            with open(path, "r", encoding="utf-8") as f:
+                return json.load(f)
+        except (FileNotFoundError, json.JSONDecodeError):
+            return None

python-client/kenaito_conf/client.py

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+import logging
+import threading
+import time
+
+import requests
+
+from kenaito_conf.cache import Cache
+from kenaito_conf.config import Config
+from kenaito_conf.crypto import decrypt_config
+from kenaito_conf.listener import Listener
+
+logger = logging.getLogger("kenaito_conf")
+
+
+class ConfigClient:
+    def __init__(self, config: Config):
+        self._config = config
+        self._cache = Cache(config.cache_dir)
+        self._listener = Listener()
+        self._configs: dict[str, str] = {}
+        self._secret: str = ""
+        self._global_secret: str = ""
+        self._last_time: int = 0
+        self._lock = threading.RLock()
+        self._stop_event = threading.Event()
+        self._started = False
+
+    def on_change(self, handler) -> None:
+        self._listener.on_change(handler)
+
+    def get(self, key: str) -> str | None:
+        with self._lock:
+            return self._configs.get(key)
+
+    def get_all(self) -> dict[str, str]:
+        with self._lock:
+            return dict(self._configs)
+
+    def start(self) -> None:
+        with self._lock:
+            if self._started:
+                return
+            self._started = True
+
+        try:
+            self._fetch_all()
+        except Exception as e:
+            logger.warning("[ConfigClient] fetch all configs error: %s, trying cache", e)
+            cached = self._cache.read()
+            if cached is not None:
+                self._apply_configs(cached)
+                logger.info("[ConfigClient] loaded %d configs from cache", len(self._configs))
+            else:
+                raise RuntimeError(f"fetch configs failed and no cache: {e}") from e
+
+        t = threading.Thread(target=self._sync_loop, daemon=True)
+        t.start()
+
+    def stop(self) -> None:
+        self._stop_event.set()
+
+    def _fetch_all(self) -> None:
+        url = (
+            f"{self._config.base_url}/api/fetchAllConfigs"
+            f"?appName={self._config.app_name}"
+            f"&env={self._config.env}"
+            f"&version={self._config.version}"
+            f"&ignoreGlobal={str(self._config.ignore_global).lower()}"
+        )
+        resp = requests.get(url, timeout=10)
+        resp.raise_for_status()
+        data = resp.json()
+
+        if data.get("code", 0) != 0:
+            raise RuntimeError(f"server error: {data.get('msg', 'unknown')}")
+
+        secret = data.get("kenaito.config.encrypt-secret")
+        if secret:
+            self._secret = secret
+
+        global_secret = data.get("kenaito.config.global-encrypt-secret")
+        if global_secret:
+            self._global_secret = global_secret
+
+        ts = data.get("latest.fetch.timestamp")
+        if ts:
+            self._last_time = int(ts)
+
+        self._cache.write(data)
+        self._apply_configs(data)
+        logger.info("[ConfigClient] fetched %d configs", len(self._configs))
+
+    def _fetch_changed(self) -> None:
+        url = f"{self._config.base_url}/api/fetchChangedConfigs"
+        payload = {
+            "appName": self._config.app_name,
+            "env": self._config.env,
+            "version": self._config.version,
+            "lastTime": self._last_time,
+            "ignoreGlobal": self._config.ignore_global,
+        }
+        resp = requests.post(url, json=payload, timeout=10)
+        resp.raise_for_status()
+        result = resp.json()
+
+        if result.get("code", -1) != 0:
+            raise RuntimeError(f"server error code: {result.get('code')}")
+
+        changed_data = result.get("data", {})
+
+        ts = changed_data.pop("latest.fetch.timestamp", None)
+        if ts:
+            self._last_time = int(ts)
+
+        if changed_data:
+            changed = {}
+            for k, v in changed_data.items():
+                decrypted = self._try_decrypt(v)
+                changed[k] = decrypted
+
+            with self._lock:
+                self._configs.update(changed)
+
+            self._listener.notify(changed)
+            logger.info("[ConfigClient] %d configs changed", len(changed))
+
+    def _apply_configs(self, data: dict) -> None:
+        with self._lock:
+            for k, v in data.items():
+                if k.startswith("kenaito.") or k == "latest.fetch.timestamp":
+                    continue
+                if not isinstance(v, str):
+                    continue
+                self._configs[k] = self._try_decrypt(v)
+
+    def _try_decrypt(self, value: str) -> str:
+        decrypted = decrypt_config(self._secret, value)
+        if decrypted == value and self._global_secret:
+            decrypted = decrypt_config(self._global_secret, value)
+        return decrypted
+
+    def _sync_loop(self) -> None:
+        while not self._stop_event.is_set():
+            self._stop_event.wait(self._config.sync_interval)
+            if self._stop_event.is_set():
+                break
+            try:
+                self._fetch_changed()
+            except Exception:
+                logger.exception("[ConfigClient] sync error")

python-client/kenaito_conf/config.py

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+class Config:
+    def __init__(
+        self,
+        base_url: str = "",
+        app_name: str = "",
+        env: str = "dev",
+        version: str = "latest",
+        token: str = "",
+        sync_interval: int = 60,
+        ignore_global: bool = False,
+        cache_dir: str = ".",
+    ):
+        self.base_url = base_url
+        self.app_name = app_name
+        self.env = env
+        self.version = version
+        self.token = token
+        self.sync_interval = sync_interval
+        self.ignore_global = ignore_global
+        self.cache_dir = cache_dir

python-client/kenaito_conf/crypto.py

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+import base64
+import hashlib
+
+import pyaes
+
+CRYPT_PREFIX = "{Cipher}"
+
+
+def decrypt_config(secret: str, data: str) -> str:
+    if not data.startswith(CRYPT_PREFIX):
+        return data
+    encrypted = data[len(CRYPT_PREFIX):]
+    return decrypt_with_aes(secret, encrypted)
+
+
+def decrypt_with_aes(key: str, data: str) -> str:
+    md5_hash = hashlib.md5(key.encode()).hexdigest()
+    aes_key = md5_hash[16:].encode()
+
+    cipher_text = base64.b64decode(data)
+
+    iv = b"\0" * 16
+    aes_cbc = pyaes.AESModeOfOperationCBC(aes_key, iv=iv)
+    plain_text = aes_cbc.decrypt(cipher_text)
+
+    padding = plain_text[-1]
+    plain_text = plain_text[:-padding]
+
+    return plain_text.decode()

python-client/kenaito_conf/listener.py

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+import logging
+import threading
+from typing import Callable
+
+ChangeHandler = Callable[[dict[str, str]], None]
+
+logger = logging.getLogger("kenaito_conf")
+
+
+class Listener:
+    def __init__(self):
+        self._handlers: list[ChangeHandler] = []
+        self._lock = threading.Lock()
+
+    def on_change(self, handler: ChangeHandler) -> None:
+        with self._lock:
+            self._handlers.append(handler)
+
+    def notify(self, changed: dict[str, str]) -> None:
+        with self._lock:
+            handlers = list(self._handlers)
+        for h in handlers:
+            try:
+                h(changed)
+            except Exception:
+                logger.exception("[ConfigClient] change handler error")

python-client/pyproject.toml

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+[build-system]
+requires = ["setuptools>=68.0", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "kenaito-conf"
+version = "1.0.0"
+description = "Kenaito Config Center Python Client"
+requires-python = ">=3.10"
+dependencies = [
+    "requests>=2.28",
+    "pyaes>=1.6",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=7.0",
+]