feat: Complete watchlist & auto-download system with UI

Implement comprehensive watchlist system with automatic episode detection
and downloading. Features include per-user watchlists, scheduler-based
periodic checks, and a modern web UI.

**Backend Components:**
- WatchlistManager: JSON-based storage with multi-tenant support
- EpisodeChecker: Detects and downloads new episodes automatically
- AutoDownloadScheduler: APScheduler-based periodic task execution
- Complete REST API for CRUD operations and scheduler control

**Frontend Components:**
- Modern watchlist page with dark theme and animations
- Real-time status updates and progress tracking
- Scheduler controls with next-run display
- Add anime directly from search results

**Models & Configuration:**
- WatchlistItem with status, quality, and auto-download settings
- WatchlistSettings for global configuration
- Per-user statistics and provider tracking

**API Endpoints:**
- GET/POST /api/watchlist - List and add items
- PUT/DELETE /api/watchlist/{id} - Update and delete
- POST /api/watchlist/{id}/check - Manual check trigger
- POST /api/watchlist/check-all - Check all due items
- GET/PUT /api/watchlist/settings - Global settings
- GET /api/watchlist/stats - Statistics
- GET/POST /api/watchlist/scheduler/* - Scheduler control

**Configuration Files:**
- config/watchlist.json - User watchlist data
- config/watchlist_settings.json - Global settings

Generated with [Claude Code](https://claude.ai/code)
Co-Authored-By: Claude <noreply@anthropic.com>

app/episode_checker.py

@@ -4,6 +4,7 @@ from typing import List, Optional, Dict
 from datetime import datetime
 
 from app.watchlist import watchlist_manager, WatchlistManager
+from app.models import DownloadRequest, DownloadTask, DownloadStatus
 from app.models.watchlist import (
     WatchlistItem,
     WatchlistSettings,
@@ -124,12 +125,11 @@ class EpisodeChecker:
                     download_link, filename = await downloader.get_download_link(ep_info.episode_url)
 
                     # Create download task
-                    task = await self.download_manager.add_download(
-                        url=download_link,
-                        filename=filename
-                    )
-
+                    request = DownloadRequest(url=download_link, filename=filename)
+                    task = self.download_manager.create_task(request)
+                    
                     if task:
+                        await self.download_manager.start_download(task.id)
                         result.episodes_downloaded.append(ep_info.episode_number)
                         logger.info(f"Started download: {filename}")
                     else: