feat(scan): 添加自定义扫描目录选择功能

- 在扫描页面添加目录输入框和选择按钮
- 实现文件系统浏览器，支持Windows盘符和目录浏览
- 添加扫描目录参数传递到后端服务
- 显示当前扫描目录路径信息
- 修复前端空数组访问错误
- 更新文档说明扫描功能变化

frontend/src/views/Scan.vue

@@ -6,10 +6,24 @@
 
         <div class="scan-tip">
             <i class="el-icon-warning-outline"></i>
-            点击开始后，程序将扫描当前运行目录并自动归类媒体文件（<b>会移动文件</b>，整理前请先备份）。
+            点击开始后，程序将扫描所选目录并自动归类媒体文件（<b>会移动文件</b>，整理前请先备份）。
             整理期间请保持服务运行，结束后可在「媒体库」查看结果。
         </div>
 
+        <div class="scan-form">
+            <div class="form-row">
+                <span class="form-label">扫描目录</span>
+                <el-input
+                        v-model="scanDir"
+                        placeholder="留空则扫描程序当前运行目录，例如 D:\media 或 /Users/me/Pictures"
+                        clearable
+                        size="medium"
+                        @keyup.enter.native="handleStart">
+                    <el-button slot="append" icon="el-icon-folder-opened" @click="openDirPicker">选择目录</el-button>
+                </el-input>
+            </div>
+        </div>
+
         <div class="scan-actions">
             <el-button
                     v-if="status.state !== 'running'"
@@ -41,9 +55,64 @@
                 :closable="false"
                 class="state-alert"/>
 
+        <el-dialog
+                title="选择要整理的目录"
+                :visible.sync="dirPickerVisible"
+                width="520px"
+                append-to-body>
+            <div class="dir-picker">
+                <div class="dir-nav">
+                    <el-button
+                            v-if="fsData.drives && fsData.drives.length"
+                            size="mini"
+                            icon="el-icon-refresh"
+                            @click="loadFs('')">盘符</el-button>
+                    <el-button
+                            v-else-if="fsData.current"
+                            size="mini"
+                            icon="el-icon-back"
+                            :disabled="fsData.parent === fsData.current"
+                            @click="loadFs(fsData.parent)">上一级</el-button>
+                    <span class="dir-path" :title="fsData.current">{{ fsData.current || '选择磁盘' }}</span>
+                </div>
+
+                <div v-if="fsData.drives && fsData.drives.length" class="dir-list">
+                    <div
+                            v-for="d in fsData.drives"
+                            :key="d"
+                            class="dir-item"
+                            @click="loadFs(d)">
+                        <i class="el-icon-folder"></i>
+                        <span>{{ d }}</span>
+                    </div>
+                </div>
+
+                <div v-else class="dir-list" v-loading="dirLoading">
+                    <div
+                            v-for="d in fsData.dirs"
+                            :key="d.path"
+                            class="dir-item"
+                            @dblclick="loadFs(d.path)">
+                        <i class="el-icon-folder"></i>
+                        <span>{{ d.name }}</span>
+                    </div>
+                    <div v-if="!dirLoading && fsData.dirs.length === 0" class="dir-empty">此目录下没有子目录</div>
+                </div>
+            </div>
+
+            <div slot="footer">
+                <el-button @click="dirPickerVisible = false">取消</el-button>
+                <el-button
+                        type="primary"
+                        :disabled="!fsData.current"
+                        @click="confirmDir">选中此目录</el-button>
+            </div>
+        </el-dialog>
+
         <div class="log-panel">
             <div class="log-header">
                 <span>运行日志</span>
+                <span class="muted" v-if="status.rootDir">扫描目录：{{ status.rootDir }}</span>
                 <span class="muted" v-if="status.started">开始于 {{ status.started }}</span>
             </div>
             <div ref="logBox" class="log-body" v-loading="status.state === 'running'">
@@ -62,14 +131,24 @@ export default {
     data() {
         return {
             starting: false,
+            scanDir: localStorage.getItem('scan-dir') || '',
             status: {
                 state: 'idle',
                 message: '',
                 started: '',
                 elapsed: 0,
+                rootDir: '',
                 lines: []
             },
-            pollTimer: null
+            pollTimer: null,
+            dirPickerVisible: false,
+            dirLoading: false,
+            fsData: {
+                current: '',
+                parent: '',
+                drives: [],
+                dirs: []
+            }
         }
     },
     mounted() {
@@ -99,7 +178,8 @@ export default {
         async handleStart() {
             this.starting = true
             try {
-                const res = await request.post('/api/scan/start')
+                localStorage.setItem('scan-dir', this.scanDir)
+                const res = await request.post('/api/scan/start', { dir: this.scanDir.trim() })
                 this.status = res.data || this.status
                 this.startPoll()
                 this.$message.success('已开始扫描整理')
@@ -107,6 +187,27 @@ export default {
                 this.starting = false
             }
         },
+        openDirPicker() {
+            this.dirPickerVisible = true
+            this.loadFs(this.scanDir.trim())
+        },
+        async loadFs(dir) {
+            this.dirLoading = true
+            try {
+                const res = await request.get('/api/fs/list', { params: dir ? { dir } : {} })
+                this.fsData = res.data || { current: '', parent: '', drives: [], dirs: [] }
+            } catch (e) {
+                // 拦截器已提示
+            } finally {
+                this.dirLoading = false
+            }
+        },
+        confirmDir() {
+            if (!this.fsData.current) return
+            this.scanDir = this.fsData.current
+            localStorage.setItem('scan-dir', this.scanDir)
+            this.dirPickerVisible = false
+        },
         startPoll() {
             this.stopPoll()
             this.pollTimer = setInterval(() => this.loadStatus(), 1000)
@@ -144,6 +245,77 @@ export default {
     margin-right: 4px;
 }
 
+.scan-form {
+    margin-bottom: 20px;
+}
+
+.form-row {
+    display: flex;
+    align-items: center;
+    gap: 12px;
+    max-width: 640px;
+}
+
+.form-label {
+    flex-shrink: 0;
+    font-size: 13px;
+    font-weight: 600;
+    color: #1f3a6b;
+}
+
+.dir-picker .dir-nav {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    margin-bottom: 10px;
+}
+
+.dir-picker .dir-path {
+    flex: 1;
+    overflow: hidden;
+    white-space: nowrap;
+    text-overflow: ellipsis;
+    font-size: 13px;
+    color: #4a5a78;
+    background: #f5f7fa;
+    border-radius: 4px;
+    padding: 6px 10px;
+}
+
+.dir-picker .dir-list {
+    height: 320px;
+    overflow-y: auto;
+    border: 1px solid #ebeef5;
+    border-radius: 6px;
+    padding: 6px;
+}
+
+.dir-picker .dir-item {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    padding: 8px 10px;
+    border-radius: 4px;
+    cursor: pointer;
+    font-size: 13px;
+    color: #303133;
+}
+
+.dir-picker .dir-item:hover {
+    background: #f0f6ff;
+}
+
+.dir-picker .dir-item .el-icon-folder {
+    color: #faad14;
+}
+
+.dir-picker .dir-empty {
+    padding: 30px 0;
+    text-align: center;
+    color: #909399;
+    font-size: 13px;
+}
+
 .scan-actions {
     margin-bottom: 20px;
 }