v2.6.0

v2.6.0 — transcoder leak fix + map rewrite

Fixed:

  - Goroutine leak in transcoder retry loop. mirrorTranscodeMetadata
    was spawned with the outer transcoder ctx instead of a per-
    invocation child, so every source reconnect cycle leaked one
    mirror goroutine + its references. Production accumulated
    1052 leaked goroutines and 777 MB RSS over ~73 hours.
    Fix: per-invocation context, defer-cancel.

  - Transcoder auto-restart gap reduced from ~2 minutes to ~5 s.
    The decoder hub pump's exit didn't close the orphaned PCM
    fanout stream; subscribers stayed blocked until HealthMonitor
    swept the stale entry after 2 minutes. Pump's defer now
    RemoveStream's the PCM mount.

Changed:

  - Dashboard + kiosk maps rewritten on MapLibre GL JS pointing
    at openfreemap.org. The previous Leaflet + CARTO setup re-flew
    the camera and re-created markers on every SSE tick — never
    settled. New shared <LiveGeoMap> diffs markers in place and
    only refits the camera when the set of cities changes.