feat(host): virtual DualSense via UHID (hid-playstation) — device + report mapping

Roadmap #5 (rich DualSense). A UHID device presents a real Sony DualSense to the kernel's
hid-playstation driver (matched by VID 054C/PID 0CE6), which exposes the full controller —
gamepad, motion sensors, touchpad, lightbar/player LEDs, adaptive triggers — unlike the
uinput X-Box-360 pad.

- inject/dualsense.rs: hand-rolled /dev/uhid codec (no bindgen) mirroring the uinput style;
  the canonical inputtino 232-byte USB HID report descriptor + the feature-report replies
  (calibration 0x05 / pairing 0x09 / firmware 0x20) — answering hid-playstation's GET_REPORTs
  during init is REQUIRED or it creates no input devices. DsState::from_gamepad maps a
  GameStream/XInput frame → the DualSense input report (buttons/sticks/triggers/dpad, +
  touchpad/motion fields); service() answers GET_REPORTs and parses HID OUTPUT (rumble /
  lightbar RGB / player LEDs / adaptive triggers) into quic::HidOutput.
- scripts/60-punktfunk.rules: grant /dev/uhid to the 'input' group (like /dev/uinput).
- `punktfunk-host dualsense-test`: standalone validation (no streaming session).

Validated live: `dualsense-test` → hid-playstation binds + loads ff_memless + led_class_
multicolor; the kernel creates "Punktfunk DualSense 0" (event/js gamepad + Motion Sensors +
Touchpad + Headset Jack) at VID 054c/PID 0ce6, plus the lightbar at /sys/class/leds/
input*:rgb:indicator; js shows the Cross button firing + the left-stick sweep. Clippy/fmt
clean, workspace tests green. Wiring into the session (pad-type select, touchpad/motion
routing, HID-output back-channel) is the next commit.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/punktfunk-host/src/inject.rs

@@ -253,6 +253,8 @@ fn gs_button_to_evdev(b: u32) -> Option<u32> {
     })
 }
 
+#[cfg(target_os = "linux")]
+pub mod dualsense;
 #[cfg(target_os = "linux")]
 pub mod gamepad;
 /// Stub — virtual gamepads need Linux uinput; events are dropped elsewhere.