Fix iOS AHRS filter init, mag heading, rest, and ZUPT

[dpyeates]

Get the iOS 18-state GPS/INS EKF working correctly before a full Android feature port.

Filter (fusionml/src/uNavINS)

• Initialize only on finite, plausible accel/mag; clamp |ax| > g; atan2 heading; skip mag if the field is unusable
• Allow init when dt <= 0 (first iOS IMU sample), then return without propagating
• Mag heading is tilt-compensated; inclination is compared in NED; no yaw correction when banked past ~30°
• Mag LPF/timer live on the instance (reset-safe); Kalman mag-bias states are not mixed with the LPF
• GPS measurement is 6×6 with a gross-outlier gate; first fix accepted on TOW or non-origin lat/lon
• Rest uses a 1 s sliding window plus gyro mean-magnitude, and exits on ~0.17 s of motion
• ZUPT triggers from fresh GPS speed; when GPS confirms a stop it can pull back a diverged INS
• Weak 1 g accelerometer tilt aid to relevel after turns (excluded during nG coordinated turns)
• Baro fused at 5 Hz; unused IMU delay buffer removed

iOS

• attitudeValid from isInitialized() + finite + health; no extra landscape heading offset
• Declination has an explicit hasDeclination flag; poor hacc does not invent velocity
• Playback applies WMM; X-Plane first TOW is nonzero
• Emits atRest and zuptActive on each AHRS update

Android

• JNI now calls uNavINS (the old fusion/ EKF is gone)
• Kotlin implements the current Turbo Module spec, including recording stubs
• Emits the same AhrsData fields as iOS (health, rest, ZUPT, declination, track/speed)
• Location accuracy uses API 26+ speedAccuracyMetersPerSecond / verticalAccuracyMeters

Example app

• Shows filter health, IMU rest, ZUPT, magnetic vs true heading, ground track, and NED velocity
• PFD overlay reads ALIGNING until attitudeValid
• RN 0.83 TypeScript config added so the example typechecks against library source
• Packages updated on the RN 0.83 line: React Native 0.83.10, React 19.2.8, Skia 2.9.1 (not 2.11, which needs Reanimated 4)

Tests

• Init/safety (including cardinal magnetic headings 0/90/180/270), static (desk, handheld, pickup), walking
• Car: cruise, accel, brake, level 90° and 360° turns, stoplight ZUPT, urban GPS (no climb/descent)
• Aircraft: cruise, accel/decel, climb, descent, coordinated / climbing / descending turns, 360° horizon, baro, GPS outage
• Vertical and horizontal FPA, crab, ground track, NED velocity, lat/lon — eastbound heading and HFPA asserts are kept
• Plant magnetometer is a real NED→body rotation of the World WMM field (bn/be/bd), not my = B·sin(heading) (that flipped 90° to 270°)
• Plant matches iOS: 60 Hz IMU, GPS frozen between 1 Hz (ground) / 5 Hz (air) fixes, first sample dt = 0
• yarn test:fusion runs in GitHub CI (128 uNavINS asserts, 0 failed)

CI

• Turbo 2 pipeline renamed to tasks; ESLint Flow plugin; example app ignored
• iOS job pinned to macos-15 + Xcode 16.4 (macos-latest is Xcode 26-only)
• iOS uses pod update so RN 0.83.10 can move fmt 11.0.2 → 12.1.0
• Android writes sdk.dir and installs NDK 27.1 via sdkmanager (Gradle zip download was corrupt)

Packaging

• package.json ships fusionml; podspec includes XYZgeomag.hpp

Android recording/playback is still stubbed. The filter path now matches iOS.