feat: 新增 C++ 和 Rust 客户端 SDK 及 Docker 构建支持

- 新增 kenaito-conf-cpp-client / kenaito-conf-rust-client 及对应 demo
- 新增 Dockerfile.cpp / Dockerfile.rust
- README 目录结构补充 C++/Rust 客户端
- README_DOCKERFILE 补充 Windows docker run 命令，新增 C++/Rust 段落

kenaito-conf-rust-client-demo/src/main.rs

@@ -0,0 +1,85 @@
+use kenaito_conf_client::{Client, Config};
+use std::collections::HashMap;
+use std::env;
+use std::sync::Arc;
+use std::thread;
+use std::time::Duration;
+
+fn get_env(key: &str, default: &str) -> String {
+    env::var(key).unwrap_or_else(|_| default.to_string())
+}
+
+fn get_env_int(key: &str, default: u64) -> u64 {
+    env::var(key)
+        .ok()
+        .and_then(|v| v.parse().ok())
+        .unwrap_or(default)
+}
+
+fn main() {
+    let config_values: HashMap<String, String> = [
+        ("database.host".to_string(), "192.168.1.1".to_string()),
+        ("database.port".to_string(), "8888".to_string()),
+        ("database.name".to_string(), "xxxx".to_string()),
+        ("database.user".to_string(), "xxxx".to_string()),
+        ("database.password".to_string(), "xxxxxxxx".to_string()),
+    ]
+    .iter()
+    .cloned()
+    .collect();
+
+    let config = Config {
+        base_url: get_env("KENAITO_BASE_URL", "http://localhost:8080"),
+        app_name: get_env("KENAITO_APP_NAME", "kenaito-springboot-demo"),
+        env: get_env("KENAITO_ENV", "daily"),
+        version: get_env("KENAITO_VERSION", "latest"),
+        token: get_env("KENAITO_TOKEN", ""),
+        sync_interval: get_env_int("KENAITO_SYNC_INTERVAL", 10),
+        cache_dir: get_env("KENAITO_CACHE_DIR", "."),
+        ..Default::default()
+    };
+
+    let client = Arc::new(Client::new(config.clone()));
+
+    client.on_change(|changed| {
+        println!("Config changed:");
+        for (k, v) in changed {
+            println!("  {} = {}", k, v);
+        }
+    });
+
+    if let Err(e) = client.start() {
+        eprintln!("Failed to init config client, using local defaults: {}", e);
+    }
+
+    let mut config_values = config_values;
+    let remote = client.get_all();
+    for (k, v) in &remote {
+        if config_values.contains_key(k) {
+            config_values.insert(k.clone(), v.clone());
+        }
+    }
+    println!("loaded {} configs from remote", remote.len());
+
+    println!("\nCurrent configs:");
+    let mut keys: Vec<&String> = config_values.keys().collect();
+    keys.sort();
+    for k in keys {
+        println!("  {} = {}", k, config_values[k]);
+    }
+
+    println!("\nListening for config changes... (press Ctrl+C to stop)");
+
+    let client_clone = client.clone();
+    ctrlc::set_handler(move || {
+        println!("\nShutting down...");
+        client_clone.stop();
+        std::process::exit(0);
+    })
+    .expect("Error setting Ctrl-C handler");
+
+    loop {
+        client.sync_once();
+        thread::sleep(Duration::from_secs(config.sync_interval));
+    }
+}