v1.1.0 — cleanup + glass-to-glass instrumentation + buffer cap

Comprehensive cleanup of HTTP-streaming-era dead code, deep
instrumentation for the 'where does latency live' question, the
snapshot quality bump, and a configurable Node-side buffer cap with
destroy+reconnect on overrun.

Major changes since v1.0.0:

- Phase 1/2 cleanup: deleted ~200 lines of dead code across firmware
  (X-Frame-Seq, X-Frame-Drop, Server-Timing, TCP_NODELAY on /frame,
  s_last_painted_seq, s_last_post_us) and script (http.Agent pool,
  httpRequest helper, frameSeq Map). Comments rewritten throughout
  to reflect the streaming pivot, not the HTTP-streaming era.
- Phase 3 timing trace: per-stage 'since-event' anchored logging
  for both snapshot and stream paths. Confirms parallel startup and
  isolates where wall-clock goes between event arrival and first
  paint.
- Phase 4 glass-to-glass: extended TCP stream header from 8 → 16
  bytes with VPRT magic + per-frame event_us_low. Firmware echoes
  the most-recent painted frame's event_us_low via /state's new
  'stream' sub-object. Script polls /state and computes display
  age live.
- Phase 5 snapshot quality: sharp settings overhaul — quality
  100 ceiling, 4:4:4 chroma at jpegQuality≤2. mozjpeg disabled
  (was 4x slower for 5% file size win nobody could see).
- Phase 6 perf playbook: TESTING.md documents the capture
  methodology + alarm thresholds. UDP-vs-TCP rationale comment
  in stream_server.c so the decision isn't re-litigated.
- Listener leak fix: globalThis cleanup of orphaned cam.listen()
  registrations across script reloads (same pattern as the
  setInterval fix in v1.0.0).
- Sent-vs-painted unified log: one line per 10s window combining
  Scrypted-side counters with firmware-side window stats from
  /state polling.
- node_buf cap with destroy+reconnect: configurable Max
  Scrypted-side buffer (MB) setting. When Node's TCP write queue
  exceeds the cap, the stream socket is destroyed; firmware's
  accept loop picks up the next connection within ~500ms and the
  pipeline restarts on a fresh frame. Default 20MB.
- Settings page Status (live): sequential /state + /config fetches
  with 3s timeout (was parallel + 1.5s, which collided with the
  reduced max_open_sockets=2).

Tested at 22-25 fps painted with sub-second snapshot first-paint,
g2g matching the configured buffer cap, and zero stale-painted
frames in steady state thanks to FIONREAD skip on the firmware.