feat(editor-app): 添加外部文件修改检测

- 新增 ExternalModificationDialog 组件
- TauriFileAPI 支持 getFileMtime
- 场景文件被外部修改时提示用户

packages/editor-app/src/adapters/TauriFileAPI.ts

@@ -38,4 +38,8 @@ export class TauriFileAPI implements IFileAPI {
     public async pathExists(path: string): Promise<boolean> {
         return await TauriAPI.pathExists(path);
     }
+
+    public async getFileMtime(path: string): Promise<number> {
+        return await TauriAPI.getFileMtime(path);
+    }
 }

packages/editor-app/src/components/ExternalModificationDialog.tsx

@@ -0,0 +1,58 @@
+import { AlertTriangle, X, RefreshCw, Save } from 'lucide-react';
+import '../styles/ConfirmDialog.css';
+
+interface ExternalModificationDialogProps {
+    sceneName: string;
+    onReload: () => void;
+    onOverwrite: () => void;
+    onCancel: () => void;
+}
+
+/**
+ * 外部修改对话框
+ * External Modification Dialog
+ *
+ * 当场景文件被外部修改时显示，让用户选择操作
+ * Shown when scene file is modified externally, let user choose action
+ */
+export function ExternalModificationDialog({
+    sceneName,
+    onReload,
+    onOverwrite,
+    onCancel
+}: ExternalModificationDialogProps) {
+    return (
+        <div className="confirm-dialog-overlay" onClick={onCancel}>
+            <div className="confirm-dialog external-modification-dialog" onClick={(e) => e.stopPropagation()}>
+                <div className="confirm-dialog-header">
+                    <AlertTriangle size={20} className="warning-icon" />
+                    <h2>文件已被外部修改</h2>
+                    <button className="close-btn" onClick={onCancel}>
+                        <X size={16} />
+                    </button>
+                </div>
+                <div className="confirm-dialog-content">
+                    <p>
+                        场景 <strong>{sceneName}</strong> 已在编辑器外部被修改。
+                    </p>
+                    <p className="hint-text">
+                        请选择如何处理：
+                    </p>
+                </div>
+                <div className="confirm-dialog-footer external-modification-footer">
+                    <button className="confirm-dialog-btn cancel" onClick={onCancel}>
+                        取消
+                    </button>
+                    <button className="confirm-dialog-btn reload" onClick={onReload}>
+                        <RefreshCw size={14} />
+                        重新加载
+                    </button>
+                    <button className="confirm-dialog-btn overwrite" onClick={onOverwrite}>
+                        <Save size={14} />
+                        覆盖保存
+                    </button>
+                </div>
+            </div>
+        </div>
+    );
+}

packages/editor-app/src/styles/ConfirmDialog.css

@@ -126,3 +126,52 @@
 .confirm-dialog-btn:active {
   transform: scale(0.98);
 }
+
+/* External Modification Dialog | 外部修改对话框 */
+.external-modification-dialog .warning-icon {
+  color: #f0ad4e;
+  margin-right: 8px;
+  flex-shrink: 0;
+}
+
+.external-modification-dialog .confirm-dialog-header {
+  gap: 0;
+}
+
+.external-modification-dialog .confirm-dialog-header h2 {
+  flex: 1;
+}
+
+.external-modification-dialog .hint-text {
+  margin-top: 12px;
+  color: var(--text-secondary, #999);
+  font-size: 13px;
+}
+
+.external-modification-footer {
+  flex-wrap: wrap;
+}
+
+.confirm-dialog-btn.reload {
+  background: #5bc0de;
+  color: white;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.confirm-dialog-btn.reload:hover {
+  background: #7cd0e8;
+}
+
+.confirm-dialog-btn.overwrite {
+  background: #f0ad4e;
+  color: white;
+  display: flex;
+  align-items: center;
+  gap: 6px;
+}
+
+.confirm-dialog-btn.overwrite:hover {
+  background: #f4be6e;
+}