…etry, stale-replay gate

The field report ('first lap reads 7s but arrived 25s into the race') unwound
into three RH-adapter defects, diagnosed by probing the console's actual
websocket path against a live rig:

- prepare_instant_start zeroed the staging delays of the format that was
  current AT STAGE TIME — but seating the heat switches RH's effective format
  to the heat's CLASS format (RHRace's class_format_id override), so the race
  staged with STOCK multi-second staging tones + delays on top of Grid's own
  start procedure. Every race began ~5-7s after Grid's go (a DB-bloated RH
  stretched it past 15s); lap stamps stayed race-relative so results were
  self-consistent and the skew was invisible everywhere except live: laps,
  tones, and callouts all arrived that late. The prepare now re-runs right
  before stage_race, when the effective format is current and RH is READY.
  Measured on the rig: the websocket-path lap latency fell from a constant
  ~7.1s to 0.28-0.37s (median 0.32s).
- A busy RH ('Attempted to stage race while status is not ready') silently
  DROPS a stage — the race never starts and no passes record. The driver now
  re-emits stage_race every 5s inside the settle window until RH confirms
  RACING (paced above RH's stock staging so a retry can never restart a
  countdown in progress).
- Lap records drained BEFORE this arming's RACING confirmation are a stale
  replay — a busy RH re-broadcasts the PREVIOUS race's current_laps snapshot,
  and remapping it contaminated the fresh heat with the last race's laps
  (observed live: a new heat opening on lap 6+). ArmedHeat now carries a
  started flag (set on SessionStarted, shared across reconnects so mid-race
  snapshot replays still dedup) and pre-start passes are dropped.

Operational note: a long-lived test rig accumulates RH heats (one per race,
'Heat 166' by tonight) and slows staging/saves — reset the container's DB
periodically; the retry + gate make the failure mode safe rather than corrupt.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>