Add comprehensive deletion functionality and scheduled cleanup

Features:
- Delete entire channels with all videos and downloaded files
- Delete individual video files while keeping database entries
- Scheduled automatic cleanup of videos older than 7 days
- Proper cascading deletes with file cleanup

Channel Deletion:
- New DELETE endpoint at /api/channels/<id>
- Removes channel, all video entries, and downloaded files
- User ownership verification
- Returns count of deleted files
- UI button on channels page with detailed confirmation dialog

Video File Deletion:
- New DELETE endpoint at /api/videos/<id>/file
- Celery async task to remove file from disk
- Resets download status to pending (allows re-download)
- UI button on watch page for completed videos
- Confirmation dialog with clear warnings

Scheduled Cleanup:
- Celery beat configuration for periodic tasks
- cleanup_old_videos task runs daily at midnight
- Automatically deletes videos completed more than 7 days ago
- Removes files and resets database status
- scheduled_tasks.py for beat schedule configuration
- verify_schedule.py helper to check task scheduling

UI Improvements:
- Added .btn-danger CSS class (black/white theme)
- Delete buttons with loading states
- Detailed confirmation dialogs warning about permanent deletion
- Dashboard now filters to show only completed videos

Bug Fixes:
- Fixed navbar alignment issues
- Added proper error handling for file deletion

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

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

main.py

@@ -6,7 +6,7 @@ from flask_login import LoginManager, login_user, logout_user, login_required, c
 from feed_parser import YouTubeFeedParser, fetch_single_video, save_single_video_to_db
 from database import init_db, get_db_session
 from models import Channel, VideoEntry, DownloadStatus, User
-from download_service import download_video, download_videos_batch
+from download_service import download_video, download_videos_batch, delete_video_file
 from sqlalchemy import desc
 
 
@@ -157,7 +157,8 @@ def index():
         with get_db_session() as session:
             # Query videos for current user's channels, sorted by published date (newest first)
             videos = session.query(VideoEntry).join(Channel).filter(
-                Channel.user_id == current_user.id
+                Channel.user_id == current_user.id,
+                VideoEntry.download_status == DownloadStatus.COMPLETED
             ).order_by(desc(VideoEntry.published_at)).all()
 
             return render_template("dashboard.html", videos=videos)
@@ -695,7 +696,49 @@ def stream_video(video_id: int):
         return jsonify({"error": f"Failed to stream video: {str(e)}"}), 500
 
 
+@app.route("/api/videos/<int:video_id>/file", methods=["DELETE"])
+@login_required
+def delete_video(video_id: int):
+    """Delete a downloaded video file from disk.
+
+    Args:
+        video_id: Database ID of the VideoEntry
+
+    Returns:
+        JSON response indicating success or failure
+    """
+    try:
+        with get_db_session() as session:
+            # Only allow deleting videos from user's own channels
+            video = session.query(VideoEntry).join(Channel).filter(
+                VideoEntry.id == video_id,
+                Channel.user_id == current_user.id
+            ).first()
+
+            if not video:
+                return jsonify({"status": "error", "message": "Video not found"}), 404
+
+            if video.download_status != DownloadStatus.COMPLETED:
+                return jsonify({
+                    "status": "error",
+                    "message": "Video is not downloaded"
+                }), 400
+
+            # Queue deletion task
+            task = delete_video_file.delay(video_id)
+
+            return jsonify({
+                "status": "success",
+                "video_id": video_id,
+                "task_id": task.id,
+                "message": "Video deletion queued"
+            })
+    except Exception as e:
+        return jsonify({"status": "error", "message": f"Failed to delete video: {str(e)}"}), 500
+
+
 def main():
+
     """CLI entry point for testing feed parser."""
     parser = YouTubeFeedParser(DEFAULT_CHANNEL_ID)
     result = parser.fetch_feed()