Replace the macOS PTT backend's worker-thread stub (which had just
slept) with a full CGEventTap implementation:
* extern "C" bindings to CGEventTapCreate, CGEventGetIntegerValueField,
CGEventTapEnable, CFMachPortCreateRunLoopSource, CFRunLoopGetCurrent,
CFRunLoopAddSource/RemoveSource, CFRunLoopRun/Stop, CFRelease, plus
the kCFRunLoopCommonModes static.
* tap_callback: C-ABI extern fn that reads bound keycode /
mouse-button from atomics, matches the incoming event, and toggles
the AudioTransmitGate. Returns the event unchanged (listen-only
tap, no event modification). Privacy-safe: never logs raw key
codes or button numbers (DEC-027).
* Event mask covers kCGEventKeyDown, kCGEventKeyUp,
kCGEventOtherMouseDown, kCGEventOtherMouseUp; also handles the
kCGEventTapDisabledBy{Timeout,UserInput} notifications by logging
a degraded-mode warning.
* Worker thread captures the CFRunLoopRef via a Send-marked
RunLoopHandle newtype so stop() can call CFRunLoopStop from the
audio engine thread.
* Box<TapState> is leaked into the worker via a Send-marked
TapStatePtr newtype; reclaimed on worker exit so the gate's Arc
refcount stays correct.
* Flutter logical-key labels are mapped to Carbon virtual keycodes
via label_to_macos_keycode (covers letters, digits, function keys,
navigation, common punctuation). Mouse-side-button labels resolve
via label_to_macos_mouse_button (3 = Mouse4, 4 = Mouse5).
* refresh_bound_atomics() rebuilds bound_keycode + bound_mouse_button
on start() and rebind() so the tap callback sees the new binding
without re-arming the tap.
Tests: chanora_audio 34 / 0 / 0 on macOS (was 28 before this commit).
Added: keymap_letters, keymap_function_keys, keymap_navigation,
keymap_unknown_returns_none, mouse_button_map, runloop_handle_is_send.
Verified the live IOHIDCheckAccess returns Undetermined (Unknown=2) on
a fresh M1 box where Input Monitoring has never been requested; the
1.5 s permission-watcher re-publishes the descriptor on user grant
or revoke without restart.
DEC-025: macOS desktop officially in scope. SAD-073: two-level PTT
ladder. SRS-198: honest capability advertising. DEC-027: privacy.
EdisonJwa
383b707e7c