forza-trigger: remove RPM-stuck workaround + bump hysteresis to 120

Two separate causes of stationary trigger pulsing, both fixed:

1. Hysteresis too short. 30 packets (0.5s) was shorter than FH5's
   stationary oscillation period (~1s per state in start-grid/pause
   screen contexts). Bumped to 120 (2s at 60Hz).

2. RPM-stuck workaround removed entirely. Cosmii's RPM_ACCUMULATOR
   (legacy_Program.cs:89-109) forced is_race_on false after 3.3s of
   constant RPM + zero power. While stationary in-race (idle RPM
   constant, power near zero), this would trip, causing a false
   menu transition. Engine idle flutter on power could reset and
   re-trigger it, producing a slow oscillation with clicks on each
   edge. FH5 has been observed to correctly clear is_race_on between
   races (confirmed via live strace), so the workaround is unnecessary.

   Removed: RPM_ACCUMULATOR_TRIGGER_RACE_OFF constant, is_race_on's
   debounce logic, DaemonState.last_rpm and .rpm_accumulator fields.
   is_race_on is now a one-liner: return bool(is_race_on field).

Tests: 57/57 pass. TestIsRaceOn simplified from 4 to 3 tests.
DaemonState reset test no longer checks removed fields.

hosts/yarn/forza-trigger/forza_trigger.py

@@ -144,18 +144,17 @@ CAR_CLASS_COLORS = {
 }
 COLOR_CLASS_X = (105, 182, 72)  # green for above-S2
 
-# --- IsRaceOn debounce ------------------------------------------------------
-# FH5 sometimes leaves is_race_on=1 after menu transitions. Count samples
-# where RPM is stable AND power ≤ 0; once the count exceeds the threshold,
-# override is_race_on to false. ~3.3s at 60Hz packet rate. (legacy_Program.cs:35)
-RPM_ACCUMULATOR_TRIGGER_RACE_OFF = 200
+# --- Race detection ---------------------------------------------------------
 
 # Hysteresis on is_race_on flag flips. FH5 emits packets where the bit
 # alternates True/False at packet rate during menu/loading transitions.
 # This many consecutive packets of the OPPOSITE current state are required
-# before is_race_on() commits a flip. ~0.5s at 60Hz — long enough to
-# filter alternation, short enough to keep race-start/end responsive.
-IN_RACE_HYSTERESIS_PACKETS = 30
+# before commit_in_race commits a flip. Stationary in-race (start grid,
+# pause screen, post-crash reset) FH5 emits a slow ~1s oscillation that
+# 30 packets (0.5s) doesn't cover. 120 packets = 2s at 60Hz — short enough
+# that a real race-start transition still feels responsive, long enough to
+# filter the stationary oscillation.
+IN_RACE_HYSTERESIS_PACKETS = 120
 
 # --- User-facing intensity scales (env vars) --------------------------------
 # Read once at module import. Process restart picks up new values.
@@ -346,9 +345,6 @@ class DaemonState:
     # receipt). The hysteresis counter requires N consecutive packets
     # of the OPPOSITE flag value before flipping committed_in_race.
     in_race_pending_count: int = 0
-    # IsRaceOn debounce.
-    last_rpm: float = 0.0
-    rpm_accumulator: int = 0
     # Last-known valid car class / CPI. We always update on observation —
     # Cosmii's `> 0` guard treats Class-D (enum value 0) as "no info" and
     # leaves the lightbar showing the previous class color, which is wrong.
@@ -370,8 +366,7 @@ class DaemonState:
         self.last_brake_freq = 0.0
         self.was_throttle_slipping = False
         self.was_brake_slipping = False
-        self.last_rpm = 0.0
-        self.rpm_accumulator = 0
+
         self.in_race_pending_count = 0
         self.last_color = (0, 0, 0)
 
@@ -380,22 +375,19 @@ class DaemonState:
 
 
 def is_race_on(pkt: ForzaDataPacket, state: DaemonState) -> bool:
-    """Read the raw is_race_on flag with FH5's RPM-stuck-true workaround
-    (Cosmii's RPM_ACCUMULATOR debounce — legacy_Program.cs:89-109) applied.
-    Hysteresis on flag flips is the caller's job (see commit_in_race).
-    """
-    raw_flag = bool(_safe_field(pkt, "is_race_on", 0.0))
-    current_rpm = _safe_field(pkt, "current_engine_rpm", 0.0)
-    power = _safe_field(pkt, "power", 0.0)
+    """Read the is_race_on flag from the current Forza packet.
 
-    if abs(current_rpm - state.last_rpm) < 1e-3 and power <= 0:
-        state.rpm_accumulator += 1
-        if state.rpm_accumulator > RPM_ACCUMULATOR_TRIGGER_RACE_OFF:
-            raw_flag = False
-    else:
-        state.rpm_accumulator = 0
-    state.last_rpm = current_rpm
-    return raw_flag
+    FH5's per-packet oscillation on this field is handled upstream by
+    commit_in_race (hysteresis), not here. Previously we carried Cosmii's
+    RPM-stability workaround (legacy_Program.cs:89-109) which forced the
+    flag false when RPM was unchanged AND power <= 0 for 200+ packets.
+    That caused false-positive menu transitions while stationary in-race
+    (idle RPM is constant, power may hover near zero) — the daemon would
+    oscillate between race/menu states and produce audible trigger clicks.
+    FH5 has been observed to correctly set is_race_on=False between races
+    (confirmed via live strace on yarn), so the workaround is removed.
+    """
+    return bool(_safe_field(pkt, "is_race_on", 0.0))
 
 
 def commit_in_race(raw_flag: bool, state: DaemonState) -> bool: