v1.3.0 — screenshot, seek-%, synced recordings

Added

• /screenshot + a 📸 panel button — grab the current video frame.
• Seek-to-% buttons (0/25/50/75%) on the now-playing panel.
• Record toggle — the ⏺ panel button starts/stops recording; recorder reachable from /info.

Fixed

• Recording A/V sync (drop B-frames + resample audio).
• Empty/0:00 video recordings (seek clamp, E-AC3→AAC, HEVC→H.264, faststart remux).
• Volume/mute no longer restarts the video from the start.
• Friendlier /radio error when no VC is open; logging cleanup.

See CHANGELOG.md. This is the rollback point before the next round of streaming-smoothness work.