feat(apple,android): three-way touch input — trackpad cursor (default), direct pointer, real multi-touch passthrough

The two touch clients had exactly complementary gaps: iOS forwarded fingers
ONLY as raw wire touches (no way to drive the host cursor from the touch
screen), Android had the two mouse modes but no passthrough. Both now share
one three-way "Touch input" setting: Trackpad (default) / Direct pointer /
Touch passthrough.

iOS/iPadOS: Input/TouchMouse.swift ports the Android gesture engine 1:1
(same px-based acceleration curve; tap=click, two-finger tap=right-click,
two-finger drag=scroll, tap-then-drag=held drag, three-finger tap=stats
HUD via the shared hudEnabled default); direct-pointer mode maps through
the aspect-fit letterbox; the previous always-on behavior lives on as the
passthrough option. The mode latches per gesture (a Settings change never
splits one gesture across models), touchesCancelled releases held state
without synthesizing a click, and session stop flushes a mid-drag button.
Settings picker on iPhone + iPad next to the iPad-only pointer-capture
toggle. Deliberate default change: trackpad, not passthrough.

Android: new nativeSendTouch JNI shim → wire TouchDown/Move/Up (the host
already injects real touch on every backend — libei touchscreen, wlroots,
KWin fake-input, SendInput); streamTouchPassthrough forwards every finger
with stable ids and lifts still-held contacts on teardown; the trackpadMode
Boolean becomes the TouchMode enum (old pref migrated on load, never
rewritten) with a Settings dropdown.

Verified: macOS swift build + full suite (incl. new TouchMouseTests), iOS
Simulator Swift compile, cargo check/fmt/clippy on the native crate, Kotlin
app+kit compile + unit tests. On-glass feel of the iOS ballistics and
Android passthrough against a touch-aware app still pending.

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

CLAUDE.md

@@ -204,7 +204,13 @@ Low-latency desktop/game streaming stack, Linux-first, with a shared Rust protoc
    "always show scroll bars" overrides `.hidden`); launcher/settings/add-host/keyboard
    render-verified live on this Mac via `PUNKTFUNK_FORCE_GAMEPAD_UI=1` (dev hook, forces
    the mode without a pad). Controller-in-hand on-glass validation still pending on all
-   platforms. Tests: `swift test` in
+   platforms. **Touch input (iOS/iPadOS, 2026-07-02):** a 3-way model in Settings —
+   **Trackpad** (default; the Android client's gesture vocabulary ported 1:1 in
+   `Input/TouchMouse.swift`: tap=click · two-finger tap=right-click · two-finger drag=scroll ·
+   tap-then-drag=held drag · three-finger tap=HUD toggle, relative ballistics with the same
+   px-based acceleration curve), **Direct pointer** (cursor jumps to the finger), **Touch
+   passthrough** (the previous always-on behavior — real wire touches). Latched per gesture
+   from `DefaultsKey.touchMode`; not yet on-glass validated. Tests: `swift test` in
    `clients/apple` (unit + real-codec round trip),
    `test-loopback.sh` (Swift client vs synthetic punktfunk1-hosts on loopback — runs on macOS;
    includes the pairing ceremony + `--require-pairing` gate),
@@ -350,7 +356,11 @@ Low-latency desktop/game streaming stack, Linux-first, with a shared Rust protoc
    the `MulticastLock` + permission UX), SPAKE2 PIN pairing + TOFU (Keystore identity +
    known-host store), Compose UI (Connect/Settings/Stream) with D-pad/controller focus nav. Built for
    `arm64-v8a` + `x86_64`; published to Google Play (Internal Testing) via `android.yml`
-   (`ci/play-upload.py`). Next: real-device gamepad/HDR live-verify, presenter/latency polish.
+   (`ci/play-upload.py`). Touch input is the same 3-way model as iOS (2026-07-02): the existing
+   Trackpad/Direct mouse modes plus new **real multi-touch passthrough**
+   (`streamTouchPassthrough` → `nativeSendTouch` → wire TouchDown/Move/Up), a `TouchMode`
+   Settings dropdown replacing the old trackpad Boolean (migrated on load); not yet
+   on-device validated. Next: real-device gamepad/HDR live-verify, presenter/latency polish.
 2. **Sub-frame pipelining**: overlap encode and transmit within a frame. Requires a direct
    NVENC SDK wrapper (libavcodec only emits whole AUs) — the next big latency lever (~2–4 ms
    at high res).