feat(android): simulate intensity & frequency via PWM on no-amplitude devices

[piaskowyk]

Problem

On older Android phones without amplitude control (CompatibilityMode.LIMITED_SUPPORT), continuous presets all felt like one undifferentiated buzz. convertToTimingWaveform only checked intensity > 0 and collapsed each segment into a solid ON block — discarding both the intensity level and the frequency entirely.

Approach

A no-amplitude LRA/ERM driven via VibrationEffect.createWaveform(timings, -1) is the exact on/off-only equivalent of the web navigator.vibrate(array). So this ports the web engine's PWM / duty-cycle simulation (web/Pulsar/src/PatternComposer.ts + RealtimeComposer.ts):

• intensity → ON pulse length (duty cycle)
• frequency → OFF gap between pulses (inverted: higher freq = shorter gap = faster pulsing)

Changes

• New PwmTimingSimulator — shared duty-cycle math. ERM-tuned bounds with the minimum pulse floored near the actuator engagement threshold (~40 ms) so low intensities stay perceptible instead of falling into the weak-buzz dead zone (same reasoning the web RealtimeComposer documents).
• convertToTimingWaveform (static patterns/presets) — rewritten to walk the timeline and tile [shot, pause, …], sampling intensity/frequency at each pulse start. Genuine silent regions (intensity 0) stay off; pulses are clamped to the remaining duration.
• RealtimePrimitiveComposer (realtime gestures, LIMITED + API < 33) — encodes intensity as the ON pulse length instead of the ignored createOneShot amplitude, and sets the loop interval to shot + pause. API 33+ keeps scalable composition primitives, so no regression on capable devices.

Verification

• ./gradlew :Pulsar:compileDebugKotlin / :Pulsar:assembleDebug — ✅ build succeeds.
• No-amplitude vs amplitude behavior cannot be felt on the emulator — a physical ERM device is needed. Two simulation notes for a capable test phone:
  • Static path: forceHapticsSupportLevel(LIMITED_SUPPORT) still routes to the amplitude waveform on a device that has amplitude (branch is isAmplitudeSupported() && forced >= LIMITED); force NO_SUPPORT to exercise convertToTimingWaveform.
  • Realtime path: usesPwmFallback requires API < 33, so it only runs on actual old phones.

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