Parse ffmpeg's -stats progress line (speed=Yx, fps=) from the HLS encoder's
stderr into a per-session EWMA, and report a health snapshot to the web side a
few seconds after seg-0. Lets the player name a too-slow transcode from a
direct measurement (~5-7s) instead of inferring it from stall shape (~15-30s).
- hls.go: add -stats; rewrite hlsStderrCapture.Write to frame on \r and \n,
parse speed=/fps= (telemetry only, never logged), flag input-bound on source
read errors. EWMA on HLSSession + GetTranscodeStats(); warmup-skip the first
cold-start frames so a healthy encoder isn't reported as struggling.
- client.go: MarkSessionReady takes an optional *SessionHealth.
- daemon.go: watcher reports one health snapshot once >=4 post-warmup samples
settle; classifyAgentHealth maps the speed ratio to ok/marginal/struggling.
Additive: old web replicas ignore the extra field; cache-hit/direct-play
sessions and short encodes report nil (the web keeps its stall heuristic).
