feat(video): add streamable video events & dashboard controls

Add end-to-end support for video events: server streaming, scheduler
metadata, API fields, and dashboard UI.

- Server: range-capable streaming endpoint with byte-range support.
- Scheduler: emits `video` object; best-effort HEAD probe adds
  `mime_type`, `size`, `accept_ranges`; placeholders for richer
  metadata (duration/resolution/bitrate/qualities/thumbnails).
- API/DB: accept and persist `event_media_id`, `autoplay`, `loop`,
  `volume` for video events.
- Frontend: Event modal supports video selection + playback options;
  FileManager increased upload size and client-side duration check
  (max 10 minutes).
- Docs/UX: bumped program-info, added UX-only changelog and updated
  Copilot instructions for contributors.
- Notes: metadata extraction (ffprobe), checksum persistence, and
  HLS/DASH transcoding are recommended follow-ups (separate changes).

server/routes/eventmedia.py

@@ -1,5 +1,5 @@
 from re import A
-from flask import Blueprint, request, jsonify, send_from_directory
+from flask import Blueprint, request, jsonify, send_from_directory, Response, send_file
 from server.permissions import editor_or_higher
 from server.database import Session
 from models.models import EventMedia, MediaType, Conversion, ConversionStatus
@@ -7,6 +7,7 @@ from server.task_queue import get_queue
 from server.worker import convert_event_media_to_pdf
 import hashlib
 import os
+import re
 
 eventmedia_bp = Blueprint('eventmedia', __name__, url_prefix='/api/eventmedia')
 
@@ -304,3 +305,63 @@ def get_media_by_id(media_id):
     }
     session.close()
     return jsonify(result)
+
+
+# --- Video Streaming with Range Request Support ---
+@eventmedia_bp.route('/stream/<int:media_id>/<path:filename>', methods=['GET'])
+def stream_video(media_id, filename):
+    """Stream video files with range request support for seeking"""
+    session = Session()
+    media = session.query(EventMedia).get(media_id)
+    if not media or not media.file_path:
+        session.close()
+        return jsonify({'error': 'Video not found'}), 404
+    
+    file_path = os.path.join(MEDIA_ROOT, media.file_path)
+    if not os.path.exists(file_path):
+        session.close()
+        return jsonify({'error': 'File not found'}), 404
+    
+    session.close()
+    
+    # Determine MIME type based on file extension
+    ext = os.path.splitext(filename)[1].lower()
+    mime_types = {
+        '.mp4': 'video/mp4',
+        '.webm': 'video/webm',
+        '.ogv': 'video/ogg',
+        '.avi': 'video/x-msvideo',
+        '.mkv': 'video/x-matroska',
+        '.mov': 'video/quicktime',
+        '.wmv': 'video/x-ms-wmv',
+        '.flv': 'video/x-flv',
+        '.mpg': 'video/mpeg',
+        '.mpeg': 'video/mpeg',
+    }
+    mime_type = mime_types.get(ext, 'video/mp4')
+    
+    # Support range requests for video seeking
+    range_header = request.headers.get('Range', None)
+    if not range_header:
+        return send_file(file_path, mimetype=mime_type)
+    
+    size = os.path.getsize(file_path)
+    byte_start, byte_end = 0, size - 1
+    
+    match = re.search(r'bytes=(\d+)-(\d*)', range_header)
+    if match:
+        byte_start = int(match.group(1))
+        if match.group(2):
+            byte_end = int(match.group(2))
+    
+    length = byte_end - byte_start + 1
+    
+    with open(file_path, 'rb') as f:
+        f.seek(byte_start)
+        data = f.read(length)
+    
+    response = Response(data, 206, mimetype=mime_type, direct_passthrough=True)
+    response.headers.add('Content-Range', f'bytes {byte_start}-{byte_end}/{size}')
+    response.headers.add('Accept-Ranges', 'bytes')
+    response.headers.add('Content-Length', str(length))
+    return response