Traction loss heuristic triggers when airborne (generic SimHub telemetry source)

[Mhytee]

Issue

On the generic SimHub telemetry path there is no per-wheel slip telemetry, so
traction loss infers slip with a heuristic built from three signals:

• Wheelspin: RPM rising sharply under throttle while speed isn't (gated off
  near the rev limiter).
• Slide: yaw rate exceeding what lateral g and speed can account for
  (slip-angle / centripetal mismatch).
• Confidence floor: if the game's own traction control is intervening, the
  slip estimate is raised to a minimum.

While airborne, the first two misread the state: a free-revving engine
produces exactly the RPM-rise-without-speed-rise signature, and a car
rotating in the air produces yaw with near-zero lateral g. The per-wheel fix
from #30 isn't possible on this path.

Test

In Wreckfest 2 (or another generic-path title): disable airborne ducking,
enable only traction loss. Jump, with throttle held and again with the car
rotating.

• Before fix: buzz fires mid-air. (If no buzz, re-triage this issue.)
• After fix: silent while airborne; real wheelspin and slides still trigger
  traction loss haptics.

Fix

Gate the heuristic on TelemetryFrame.Airborne: decay and bail on airborne
frames, like its existing neutral-gear gate. Depends on #32 populating the
airborne flag on this path; for titles where #32 finds no reliable airborne
signal, the heuristic keeps today's behavior.

Related: #30, #32.

[Mhytee]

Partly staged on the beta branch: TractionLossEffect now decays and bails on airborne frames. That's live on AC and Forza (which set the airborne flag), but on the generic SimHub path this issue is about, it stays inert until #32 populates the flag. So no change on generic titles yet, this one is effectively blocked on #32.