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/events.py

@@ -394,6 +394,19 @@ def create_event():
         session.commit()
         event_media_id = media.id
 
+    # Video: event_media_id und Video-Einstellungen übernehmen
+    autoplay = None
+    loop = None
+    volume = None
+    if event_type == "video":
+        event_media_id = data.get("event_media_id")
+        if not event_media_id:
+            return jsonify({"error": "event_media_id required for video"}), 400
+        # Get video-specific settings with defaults
+        autoplay = data.get("autoplay", True)
+        loop = data.get("loop", False)
+        volume = data.get("volume", 0.8)
+
     # created_by aus den Daten holen, Default: None
     created_by = data.get("created_by")
 
@@ -419,6 +432,9 @@ def create_event():
         is_active=True,
     event_media_id=event_media_id,
     slideshow_interval=slideshow_interval,
+    autoplay=autoplay,
+    loop=loop,
+    volume=volume,
     created_by=created_by,
     # Recurrence
     recurrence_rule=data.get("recurrence_rule"),
@@ -491,6 +507,13 @@ def update_event(event_id):
     event.event_type = data.get("event_type", event.event_type)
     event.event_media_id = data.get("event_media_id", event.event_media_id)
     event.slideshow_interval = data.get("slideshow_interval", event.slideshow_interval)
+    # Video-specific fields
+    if "autoplay" in data:
+        event.autoplay = data.get("autoplay")
+    if "loop" in data:
+        event.loop = data.get("loop")
+    if "volume" in data:
+        event.volume = data.get("volume")
     event.created_by = data.get("created_by", event.created_by)
     # Track previous values to decide on exception regeneration
     prev_rule = event.recurrence_rule