feat: add Jellyfin media server (jelly.pivoine.art)

Added Jellyfin stack for streaming photos and videos from HiDrive:
- Maps /mnt/hidrive/users/valknar/Pictures to /media/pictures (read-only)
- Maps /mnt/hidrive/users/valknar/Videos to /media/videos (read-only)
- Hardware transcoding support for optimal video playback
- Multi-device streaming (web, mobile, TV apps)
- Automatic media organization with metadata fetching

Jellyfin provides superior video playback compared to Filestash's
transcoding plugin, which has compatibility issues with named pipes
in containerized environments.

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

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

compose.yaml

@@ -12,6 +12,7 @@ include:
   - joplin/compose.yaml
   - vert/compose.yaml
   - paint/compose.yaml
+  - jelly/compose.yaml
   - restic/compose.yaml
   - umami/compose.yaml
   - sablier/compose.yaml