feat(api): add WebUI API server with built frontend

- Add FastAPI server with WebSocket support for real-time logs
- Add crawler management API endpoints (start/stop/status)
- Add data browsing API endpoints (list files, preview, download)
- Include pre-built WebUI assets for serving frontend

API endpoints:
- POST /api/crawler/start - Start crawler task
- POST /api/crawler/stop - Stop crawler task
- GET /api/crawler/status - Get crawler status
- WS /api/ws/logs - Real-time log streaming
- GET /api/data/files - List data files
- GET /api/data/stats - Get data statistics

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

api/routers/websocket.py

@@ -0,0 +1,151 @@
+# -*- coding: utf-8 -*-
+# Copyright (c) 2025 relakkes@gmail.com
+#
+# This file is part of MediaCrawler project.
+# Repository: https://github.com/NanmiCoder/MediaCrawler/blob/main/api/routers/websocket.py
+# GitHub: https://github.com/NanmiCoder
+# Licensed under NON-COMMERCIAL LEARNING LICENSE 1.1
+#
+# 声明：本代码仅供学习和研究目的使用。使用者应遵守以下原则：
+# 1. 不得用于任何商业用途。
+# 2. 使用时应遵守目标平台的使用条款和robots.txt规则。
+# 3. 不得进行大规模爬取或对平台造成运营干扰。
+# 4. 应合理控制请求频率，避免给目标平台带来不必要的负担。
+# 5. 不得用于任何非法或不当的用途。
+#
+# 详细许可条款请参阅项目根目录下的LICENSE文件。
+# 使用本代码即表示您同意遵守上述原则和LICENSE中的所有条款。
+
+import asyncio
+from typing import Set, Optional
+
+from fastapi import APIRouter, WebSocket, WebSocketDisconnect
+
+from ..services import crawler_manager
+
+router = APIRouter(tags=["websocket"])
+
+
+class ConnectionManager:
+    """WebSocket 连接管理器"""
+
+    def __init__(self):
+        self.active_connections: Set[WebSocket] = set()
+
+    async def connect(self, websocket: WebSocket):
+        await websocket.accept()
+        self.active_connections.add(websocket)
+
+    def disconnect(self, websocket: WebSocket):
+        self.active_connections.discard(websocket)
+
+    async def broadcast(self, message: dict):
+        """广播消息到所有连接"""
+        if not self.active_connections:
+            return
+
+        disconnected = []
+        for connection in list(self.active_connections):
+            try:
+                await connection.send_json(message)
+            except Exception:
+                disconnected.append(connection)
+
+        # 清理断开的连接
+        for conn in disconnected:
+            self.disconnect(conn)
+
+
+manager = ConnectionManager()
+
+
+async def log_broadcaster():
+    """后台任务：从队列读取日志并广播"""
+    queue = crawler_manager.get_log_queue()
+    while True:
+        try:
+            # 从队列获取日志条目
+            entry = await queue.get()
+            # 广播到所有 WebSocket 连接
+            await manager.broadcast(entry.model_dump())
+        except asyncio.CancelledError:
+            break
+        except Exception as e:
+            print(f"Log broadcaster error: {e}")
+            await asyncio.sleep(0.1)
+
+
+# 全局广播任务
+_broadcaster_task: Optional[asyncio.Task] = None
+
+
+def start_broadcaster():
+    """启动广播任务"""
+    global _broadcaster_task
+    if _broadcaster_task is None or _broadcaster_task.done():
+        _broadcaster_task = asyncio.create_task(log_broadcaster())
+
+
+@router.websocket("/ws/logs")
+async def websocket_logs(websocket: WebSocket):
+    """WebSocket 日志流"""
+    print("[WS] New connection attempt")
+
+    try:
+        # 确保广播任务在运行
+        start_broadcaster()
+
+        await manager.connect(websocket)
+        print(f"[WS] Connected, active connections: {len(manager.active_connections)}")
+
+        # 发送现有日志
+        for log in crawler_manager.logs:
+            try:
+                await websocket.send_json(log.model_dump())
+            except Exception as e:
+                print(f"[WS] Error sending existing log: {e}")
+                break
+
+        print(f"[WS] Sent {len(crawler_manager.logs)} existing logs, entering main loop")
+
+        while True:
+            # 保持连接活跃，接收心跳或任意消息
+            try:
+                data = await asyncio.wait_for(
+                    websocket.receive_text(),
+                    timeout=30.0
+                )
+                if data == "ping":
+                    await websocket.send_text("pong")
+            except asyncio.TimeoutError:
+                # 发送 ping 保持连接
+                try:
+                    await websocket.send_text("ping")
+                except Exception as e:
+                    print(f"[WS] Error sending ping: {e}")
+                    break
+
+    except WebSocketDisconnect:
+        print("[WS] Client disconnected")
+    except Exception as e:
+        print(f"[WS] Error: {type(e).__name__}: {e}")
+    finally:
+        manager.disconnect(websocket)
+        print(f"[WS] Cleanup done, active connections: {len(manager.active_connections)}")
+
+
+@router.websocket("/ws/status")
+async def websocket_status(websocket: WebSocket):
+    """WebSocket 状态流"""
+    await websocket.accept()
+
+    try:
+        while True:
+            # 每秒发送一次状态
+            status = crawler_manager.get_status()
+            await websocket.send_json(status)
+            await asyncio.sleep(1)
+    except WebSocketDisconnect:
+        pass
+    except Exception:
+        pass