feat(audio,windows): real Raw Input + low-level hook global PTT (SDD-083 / SDD-084)

The v1.0.0-rc.7 Windows backends were thread::sleep stubs that
reported optimistic L2GlobalHoldToTalk / L3GlobalWithMouseButtons
descriptors without actually registering for any global key events.
Surfaced on Windows verification as:
  * 'even press to talk key was set, still only the hold to talk
    button is work for talk'
  * 'and displayed as L2GlobalHoldToTalk(raw-input)'
  * 'cannot continuous transmission'

This commit implements the real backends:

  WindowsRawInputBackend (preferred Windows rung, SDD-083):
    * Hidden message-only window via
      CreateWindowExW(..., HWND_MESSAGE, ...).
    * RegisterRawInputDevices with RIDEV_INPUTSINK on
      Usage Page 0x01 / Usage 0x06 (keyboard) and 0x02 (mouse) so
      events fire globally — including when Chanora is unfocused.
    * WndProc handling WM_INPUT: GetRawInputData ->
      keyboard.VKey vs bound vk, or mouse.usButtonFlags vs bound
      side-button index. Down -> gate.set(true); up -> gate.set(false).
    * Dedicated chanora-rawinput thread runs GetMessageW /
      TranslateMessage / DispatchMessageW until stop() posts
      WM_QUIT via PostThreadMessageW.

  WindowsHookBackend (fallback rung, SDD-084):
    * SetWindowsHookExW(WH_KEYBOARD_LL) + WH_MOUSE_LL on a
      dedicated chanora-llhook thread.
    * Hook procs translate KBDLLHOOKSTRUCT.vkCode and
      MSLLHOOKSTRUCT.mouseData against the same shared
      AtomicBinding.
    * UnhookWindowsHookEx on teardown.

  Both backends:
    * Honest descriptor() reporting: backends start reporting
      L0Focused; level upgrades to L2 / L3 only after a real
      arming success (RegisterRawInputDevices or SetWindowsHookEx
      returning Ok). This fixes the 'L2 reported but doesn't fire'
      complaint by making the badge tell the truth — if Raw Input
      registration fails at runtime the user sees the L0Focused
      info-icon explanation sheet instead of being told L2 works.
    * AtomicBinding (class / vk / mouse_btn) for lock-free hot
      path. Translation lives in
      crates/chanora_audio/src/ptt_backends/windows_keymap.rs
      which maps Flutter LogicalKeyboardKey.keyLabel strings
      (e.g. 'Space', 'F10', 'A') to Win32 VK_* codes; mouse
      side-button bitmask strings ('mouse-side-button:8' /
      ':16') to RawInput button indices (4 / 5).
    * Per-thread context (thread_local RefCell) carries the
      gate + binding to the WndProc / hook proc without needing
      raw-pointer user-data plumbing.

  Diagnostic logging:
    * AudioEngine::start now logs default_input_config and
      default_output_config explicitly with the channels /
      sample_rate / sample_format that cpal reports, so a
      build_*_stream failure on locale-specific Windows hosts
      (reported on ko-KR Windows 11 as 'Start Audio Button not
      work') becomes diagnosable from the stderr log alone.
    * build_output_stream surfaces the requested config in the
      tracing::error! record on failure.

  Privacy (DEC-027 / SDD-090): the windows.rs and
  windows_keymap.rs hot paths NEVER log raw VKs, scan codes,
  keysyms, key labels, or button identifiers. Only the
  platform-neutral input class ('keyboard' /
  'mouse-side-button') and the backend id appear in the tracing
  stream. The SDD-090 PttSanitizer Layer is the defence-in-depth
  net but this code does not rely on it.

  Tests: 4 new windows-only unit tests in windows_keymap (ASCII
  letters / digits / Space + Fn / unknown / mouse button index).
  They compile only under cfg(target_os = "windows") so the
  Linux workspace test count is unchanged at 59/0/3.

  Cargo deps: adds windows = '0.54' (target_os = windows) with
  the feature set needed for RawInput + hooks. 0.54 matches
  the version already transitive through the workspace.

Verified on Linux: cargo check --workspace clean, cargo test
--workspace 59/0/3 (windows-gated tests skip on Linux). The
real exercise of this commit will happen on the Korean Windows
11 host (100.84.219.45) at the next build.

crates/chanora_audio/src/engine.rs

@@ -142,6 +142,11 @@ impl AudioEngine {
         mut voice_in_rx: mpsc::Receiver<InboundVoice>,
     ) -> Result<Self, AudioError> {
         let host = cpal::default_host();
+        info!(
+            target: "chanora_audio",
+            host_id = ?host.id(),
+            "starting audio engine: cpal host selected"
+        );
         let in_dev = host
             .default_input_device()
             .ok_or(AudioError::NoInputDevice)?;
@@ -156,6 +161,45 @@ impl AudioEngine {
             "starting audio engine"
         );
 
+        // Log the cpal-reported default configs *before* trying to
+        // open streams, so a downstream stream-build failure can
+        // be cross-referenced against what the platform reported
+        // as its default format. Some locale / driver combinations
+        // on Windows have been observed to expose configs that
+        // accept device enumeration but reject `default_*_config`
+        // afterwards (reported on the ko-KR Windows 11 host as
+        // "Start audio button not work"). Promote what would
+        // otherwise be silent or laconic errors into structured
+        // log records the user can paste back.
+        match in_dev.default_input_config() {
+            Ok(c) => info!(
+                target: "chanora_audio",
+                channels = c.channels(),
+                sample_rate = c.sample_rate().0,
+                sample_format = ?c.sample_format(),
+                "default_input_config reported"
+            ),
+            Err(e) => warn!(
+                target: "chanora_audio",
+                error = %e,
+                "default_input_config FAILED — capture will be disabled"
+            ),
+        }
+        match out_dev.default_output_config() {
+            Ok(c) => info!(
+                target: "chanora_audio",
+                channels = c.channels(),
+                sample_rate = c.sample_rate().0,
+                sample_format = ?c.sample_format(),
+                "default_output_config reported"
+            ),
+            Err(e) => warn!(
+                target: "chanora_audio",
+                error = %e,
+                "default_output_config FAILED — output stream will fail to build"
+            ),
+        }
+
         // A.5 mobile-only preset acknowledgement. On Linux desktop
         // the flag is ignored; on Android we log it so a future cpal
         // / Oboe wiring can be observed in the diagnostic export.
@@ -702,7 +746,16 @@ where
             },
             None,
         )
-        .map_err(|e| AudioError::Backend(format!("build_output_stream: {e}")))?;
+        .map_err(|e| {
+            error!(
+                target: "chanora_audio",
+                error = %e,
+                requested_channels = config.channels,
+                requested_sample_rate = config.sample_rate.0,
+                "build_output_stream FAILED"
+            );
+            AudioError::Backend(format!("build_output_stream: {e}"))
+        })?;
     Ok(stream)
 }