Three root-cause fixes for VLC showing a black screen when opening a
stream from a different network or via Tailscale:
1. PrioritizeTail: when VLC opens an MKV/MP4 stream it immediately seeks
to the end of the file to read the container index (seekhead/moov
atom). For active torrents those end-pieces aren't downloaded yet, so
the reader blocks indefinitely. PrioritizeTail() opens a background
reader positioned at the last 5 MB, keeping those pieces at high
priority until ctx is cancelled or they finish downloading.
2. /health endpoint: GET /health returns a lightweight JSON response
{"status":"ok","streaming":bool,...} so connectivity can be tested
with a simple curl from any device before involving VLC.
3. Per-request logging: every incoming /stream request now logs the
client IP and Range header, making it trivial to confirm whether
remote/Tailscale clients are reaching the server at all.
Track the highest byte offset served by the stream server to estimate
playback progress (0-100%). A WatchReporter goroutine sends progress
to POST /api/internal/agent/watch-progress every 10s during streaming.
- Add maxByteOffset + totalFileSize to StreamServer for Range tracking
- Add FileSize() to fileProvider interface (all 3 providers)
- New WatchReporter: periodic progress reporter tied to daemon context
- New WatchProgressUpdate type with optional progress/position/duration
- Wire reporter into all 3 stream paths (task stream, disk stream, active download stream)
- Add daemon state persistence and stale resume file cleanup
- Add TriggerPoll for WebSocket resume actions
- Improve stream server with graceful shutdown and connection tracking
- Add desktop notifications for download completion
- Add media file organization with Movies/TV Shows detection
- Improve usenet downloader with progress tracking and resume support
- Add self-update package with GitHub release verification
- Downgrade tablewriter to v0.0.5 (v1.x API breaking change)
