fix(android): spawn_blocking + 2s timeout for set_audio_mode_communication

The JNI call into AudioManager.setMode() was running directly on the
tokio async thread. If the Android audio policy service is slow (e.g.
immediately after mic permission grant), this could block the runtime.
Moved to spawn_blocking with a 2s timeout; timeout and panic cases are
logged as connect:audio_mode_timeout / connect:audio_mode_panic debug
events and treated as non-fatal (we continue to audio_start).

Also removes the has_record_audio_permission call from the preflight
debug event — it was a redundant JNI round-trip that added latency and
is now captured separately in the preflight_start event context.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

desktop/src-tauri/src/engine.rs

@@ -617,9 +617,6 @@ impl CallEngine {
             serde_json::json!({
                 "t_ms": call_t0.elapsed().as_millis(),
                 "wzp_native_loaded": native_loaded,
-                "record_audio_permission": crate::android_audio::has_record_audio_permission()
-                    .map(|v| serde_json::json!(v))
-                    .unwrap_or_else(|e| serde_json::json!({ "error": e })),
             }),
         );
         if !native_loaded {
@@ -666,13 +663,15 @@ impl CallEngine {
                 "connect:audio_mode_start",
                 serde_json::json!({ "t_ms": call_t0.elapsed().as_millis() }),
             );
-            match crate::android_audio::set_audio_mode_communication() {
+            let audio_mode_task =
-                Ok(()) => crate::emit_call_debug(
+                tokio::task::spawn_blocking(crate::android_audio::set_audio_mode_communication);
+            match tokio::time::timeout(std::time::Duration::from_secs(2), audio_mode_task).await {
+                Ok(Ok(Ok(()))) => crate::emit_call_debug(
                     &app,
                     "connect:audio_mode_done",
                     serde_json::json!({ "t_ms": call_t0.elapsed().as_millis() }),
                 ),
-                Err(e) => {
+                Ok(Ok(Err(e))) => {
                     tracing::warn!("set_audio_mode_communication failed: {e}");
                     crate::emit_call_debug(
                         &app,
@@ -683,6 +682,26 @@ impl CallEngine {
                         }),
                     );
                 }
+                Ok(Err(e)) => {
+                    crate::emit_call_debug(
+                        &app,
+                        "connect:audio_mode_panic",
+                        serde_json::json!({
+                            "t_ms": call_t0.elapsed().as_millis(),
+                            "error": e.to_string(),
+                        }),
+                    );
+                }
+                Err(_) => {
+                    crate::emit_call_debug(
+                        &app,
+                        "connect:audio_mode_timeout",
+                        serde_json::json!({
+                            "t_ms": call_t0.elapsed().as_millis(),
+                            "timeout_ms": 2000,
+                        }),
+                    );
+                }
             }
         }