[slkass]

Add an opt-in Windows touchpad mouse with relative motion, tap-to-click, physical left/right clicks, two-finger scrolling and trackball inertia. Sensitivity and decay are stored per profile. A bounded worker keeps SendInput off the controller loop and releases abandoned clicks with a watchdog.

Finger hand-offs and retouches do not jump the pointer or leave stale inertia. Touchpad gestures are excluded from automatic extra-button navigation while the mouse tool is enabled, fixing the reported jump from Lab to Buttons. Shared desktop input also works with native gamepad input.

Dependencies and focused review

Stacked PR 2/7; depends on #10 and the earlier layers, starting with #9. All targets are upstream main, so GitHub's Files changed view currently includes unmerged dependencies. Review only this feature's incremental diff (commit 6ad0d3c).

Merge in the order below. Preserve the shared commit ancestry when merging, or rebase the remaining branches after squash/rebase merges so already-merged layers disappear from their diffs.

1. Controller Lab 1/7: DualSense trigger effects and timed trials #10 — DualSense trigger effects and timed trials
2. Controller Lab 2/7: touchpad mouse and trackball #11 — touchpad mouse and trackball
3. Controller Lab 3/7: Flick Stick and gyro mouse aiming #12 — Flick Stick and gyro mouse aiming
4. Controller Lab 4/7: Hair Trigger, two-stage pulls and Hip Fire #13 — Hair Trigger, two-stage pulls and Hip Fire
5. Controller Lab 5/7: configurable button debounce #14 — configurable button debounce
6. Controller Lab 6/7: local DSU motion forwarding #15 — local DSU motion forwarding
7. Controller Lab 7/7: dynamic lighting and matching touch feedback #16 — dynamic lighting and matching touch feedback

Validation

• cargo fmt --all --check
• cargo clippy --workspace --all-targets --release --locked -- -D warnings
• cargo test --workspace --locked: 263 passed, 5 driver/manual tests ignored, zero failures (Windows x64).
• DualSense hardware: mouse and trackball motion, tap, scroll, click/drag and inertia confirmed by the tester; automatic page-switch regression confirmed fixed. Unit tests cover gestures, finger hand-off, inertia cancellation and navigation.

All new tools are disabled by default. No additional dependencies are added. Cross-platform CI results are reported by GitHub checks.