feat(voice): harden Android audio and channel joins

apps/chanora_flutter/lib/src/rust/api.dart

@@ -9,8 +9,8 @@ import 'package:flutter_rust_bridge/flutter_rust_bridge_for_generated.dart';
 import 'package:freezed_annotation/freezed_annotation.dart' hide protected;
 part 'api.freezed.dart';
 
-// These functions are ignored because they are not marked as `pub`: `log_file_path`, `log_sink`, `open_log_file`, `permission_events`, `publish_permission_state`, `runtime`, `session`, `transmit_mode_from_u8`
-// These function are ignored because they are on traits that is not defined in current crate (put an empty `#[frb]` on it to unignore): `assert_fields_are_eq`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `eq`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `from`, `from`, `from`, `from`, `from`, `from`, `from`, `from`
+// These functions are ignored because they are not marked as `pub`: `log_file_path`, `log_sink`, `map_join_error_code`, `map_join_sync_state`, `open_log_file`, `permission_events`, `publish_permission_state`, `runtime`, `session`, `transmit_mode_from_u8`
+// These function are ignored because they are on traits that is not defined in current crate (put an empty `#[frb]` on it to unignore): `assert_fields_are_eq`, `assert_fields_are_eq`, `assert_fields_are_eq`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `clone`, `eq`, `eq`, `eq`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `fmt`, `from`, `from`, `from`, `from`, `from`, `from`, `from`, `from`
 // These functions are ignored (category: IgnoreBecauseExplicitAttribute): `from_kotlin_str`, `to_permission_gate`
 
 /// Return the platform-conventional log-file path as a string, or
@@ -454,6 +454,24 @@ sealed class BridgeEvent with _$BridgeEvent {
 
     /// Current release-tail in milliseconds (0..=500).
     required int releaseTailMs,
+
+    /// Last confirmed authoritative channel id.
+    BigInt? currentChannelId,
+
+    /// Non-authoritative pending join target channel id.
+    BigInt? pendingTargetChannelId,
+
+    /// Whether a new join intent is currently allowed.
+    required bool canJoin,
+
+    /// Whether leave intent is currently allowed.
+    required bool canLeave,
+
+    /// Join projection sync state.
+    required BridgeVoiceJoinSyncState joinSyncState,
+
+    /// Last stable join error code, if any.
+    BridgeVoiceJoinErrorCode? joinErrorCode,
   }) = BridgeEvent_VoiceState;
 
   /// iOS audio interruption state (SDD-101).
@@ -587,6 +605,28 @@ enum BridgeTransmitMode {
   voiceActivity,
 }
 
+/// Bridge mirror of stable join error/status codes.
+enum BridgeVoiceJoinErrorCode {
+  duplicateSameTargetCoalesced,
+  joinAlreadyPendingDifferentTarget,
+  joinDenied,
+  joinProtocolFailure,
+  joinNetworkFailure,
+  joinTimeout,
+  joinSupersededByLeave,
+  joinStaleOutcomeIgnored,
+  joinReconciledDifferentChannel,
+  joinCommandRejectedBeforeSend,
+  joinCannotStartWhileSynchronizing,
+}
+
+/// Bridge mirror of core join projection sync state.
+enum BridgeVoiceJoinSyncState {
+  ready,
+  synchronizingInitialSnapshot,
+  synchronizingReconnect,
+}
+
 /// Schema-controlled mirror of the Kotlin
 /// `AndroidPermissionRequester.PermissionState` sealed class
 /// (SDD-106 §5). Crosses the bridge as an enum so the Dart side can