feat: Auto-restore completed downloads on server restart

Scan the downloads folder on startup and recreate tasks for all video files.
This prevents losing download history when the server restarts.

- Only restores video files larger than 1MB (avoids partial files)
- Preserves original file timestamps as created/completed dates
- Generates new task IDs for restored downloads

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

main.py

@@ -32,6 +32,53 @@ app.add_middleware(
 # Initialize download manager
 download_manager = DownloadManager(download_dir="downloads", max_parallel=3)
 
+
+def restore_completed_downloads():
+    """Scan downloads directory and restore completed download tasks"""
+    from datetime import datetime
+    from pathlib import Path
+    import uuid
+
+    download_dir = Path("downloads")
+    if not download_dir.exists():
+        return
+
+    # Get all video files (exclude partial files and logs)
+    video_extensions = {'.mp4', '.mkv', '.avi', '.mov', '.wmv', '.flv', '.webm'}
+
+    for file_path in download_dir.iterdir():
+        if file_path.is_file() and file_path.suffix.lower() in video_extensions:
+            # Skip small files (likely partial or errors)
+            if file_path.stat().st_size < 1024 * 1024:  # Less than 1MB
+                continue
+
+            filename = file_path.name
+            file_size = file_path.stat().st_size
+
+            # Create a task for this file
+            task_id = str(uuid.uuid4())
+            task = DownloadTask(
+                id=task_id,
+                url="",  # No original URL
+                filename=filename,
+                host="other",
+                status=DownloadStatus.COMPLETED,
+                progress=100.0,
+                downloaded_bytes=file_size,
+                total_bytes=file_size,
+                speed=0.0,
+                file_path=str(file_path),
+                created_at=datetime.fromtimestamp(file_path.stat().st_ctime),
+                completed_at=datetime.fromtimestamp(file_path.stat().st_mtime)
+            )
+
+            download_manager.tasks[task_id] = task
+            print(f"[RESTORE] Restored completed download: {filename}")
+
+
+# Restore completed downloads on startup
+restore_completed_downloads()
+
 # Mount static files and templates
 app.mount("/static", StaticFiles(directory="static"), name="static")
 app.mount("/downloads", StaticFiles(directory="downloads"), name="downloads")