feat(native): Tier A desktop features (P5-46/36/44/43/49) + window chrome (P5-47)

Adds a `native/` module system (each feature = its own module exposing
`#[tauri::command]`s + optional `setup`; `emit_to_web` pushes DOM CustomEvents to
the web like `forward_deeplink`). Wired into generate_handler! + native::setup;
windows-crate feature union added to Cargo.toml.

- power.rs (P5-46): SetThreadExecutionState held on the main thread while a call
  is active; released on end. Cross-platform (no-op off Windows).
- jumplist.rs (P5-36): ICustomDestinationList "Recent Rooms" of IShellLink tasks
  launching the exe with a matrix: arg (existing deep-link handler opens the room).
- thumbbar.rs (P5-44): ITaskbarList3 ThumbBar Mute/Deafen/End (GDI HICONs) + a
  window subclass catching THBN_CLICKED → emit thumbbar-action.
- smtc.rs (P5-43): WinRT SystemMediaTransportControls via GetForWindow; ButtonPressed
  → smtc-action; call-state command. (Experimental for a non-media app.)
- network.rs (P5-49): INetworkListManager poll thread → emit network-changed.
- chrome.rs (P5-47): cross-platform window-control commands + set_custom_chrome
  (set_decorations) for the opt-in TDS titlebar.

NOT compile-verified locally (no Rust/Windows toolchain on the dev box) — this is
for the CI Windows compile pass (GitHub test.yml / Gitea windows runner). Expect a
possible fixup round (windows-crate feature/namespace paths, e.g. subclass APIs).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src-tauri/src/native/power.rs

@@ -0,0 +1,48 @@
+//! P5-46 — System power management (call continuity).
+//!
+//! Prevents the system from sleeping / turning off the display while a voice or
+//! video call is active, then releases the request when the call ends. The web
+//! client calls `set_call_active(true|false)` from `useTauriCallPower` as the
+//! call-embed atom transitions.
+//!
+//! Windows: `SetThreadExecutionState`. The request is per-thread and persists
+//! until cleared, so we run every set/clear on the **main thread** (via
+//! `run_on_main_thread`) to guarantee the clear cancels the matching set even
+//! though Tauri commands otherwise run on a pool thread.
+//!
+//! Other platforms are a no-op for now (macOS would use `IOPMAssertionCreate`,
+//! Linux `org.freedesktop.ScreenSaver`/`login1` inhibit) — tracked as a future
+//! extension; the command stays cross-platform so the web side is unconditional.
+
+use tauri::AppHandle;
+
+#[tauri::command]
+pub fn set_call_active(app: AppHandle, active: bool) {
+    #[cfg(target_os = "windows")]
+    {
+        let _ = app.run_on_main_thread(move || {
+            use windows::Win32::System::Power::{
+                SetThreadExecutionState, ES_CONTINUOUS, ES_DISPLAY_REQUIRED, ES_SYSTEM_REQUIRED,
+            };
+            let flags = if active {
+                ES_CONTINUOUS | ES_SYSTEM_REQUIRED | ES_DISPLAY_REQUIRED
+            } else {
+                // Clearing to ES_CONTINUOUS alone releases the sleep/display
+                // requirement while leaving no lingering per-thread state.
+                ES_CONTINUOUS
+            };
+            // Safety: FFI call with no pointers; returns the previous state,
+            // which we don't need.
+            unsafe {
+                SetThreadExecutionState(flags);
+            }
+        });
+    }
+
+    #[cfg(not(target_os = "windows"))]
+    {
+        // No-op on non-Windows platforms (see module docs). Bind the args so the
+        // signature stays identical cross-platform and no unused warnings fire.
+        let _ = (&app, active);
+    }
+}