feat: add Codec2 voice messages over LoRa mesh (iOS/macOS only)

Push-to-talk voice messaging using the Codec2 ultra-low-bitrate speech
codec, transmitted as V: prefixed packets over the existing MeshCore
LoRa mesh pipeline.

Voice recording UI (long-press send button or + menu) is gated behind
Platform.isIOS || Platform.isMacOS since the `record` package only
supports microphone capture on those platforms in this build.

Key changes:
- VoiceRecorderService: streams 8kHz mono PCM chunks via `record` package
- VoicePlayerService: decodes Codec2 bytes to WAV and plays via audioplayers
- VoiceCodecService: async Codec2 encode/decode in background isolates
- VoiceProvider: reassembles multi-packet sessions, drives playback
- VoiceMessageBubble: shows packet progress, play/stop controls
- MessagesProvider: detects V: prefix, routes to VoiceProvider
- MessagesTab: PTT long-press gesture + recording indicator (iOS/macOS)
- Message model: isVoice + voiceId fields for session tracking
- Auto-selects codec mode from radio bandwidth (700C/1200/1300 bps)
- codec2_flutter + meshcore_client switched from path to git deps

ios/Podfile.lock

@@ -1,4 +1,9 @@
 PODS:
+  - audioplayers_darwin (0.0.1):
+    - Flutter
+    - FlutterMacOS
+  - codec2_flutter (0.1.0):
+    - Flutter
   - device_info_plus (0.0.1):
     - Flutter
   - DKImagePickerController/Core (4.3.9):
@@ -61,6 +66,8 @@ PODS:
     - FlutterMacOS
   - permission_handler_apple (9.3.0):
     - Flutter
+  - record_ios (1.2.0):
+    - Flutter
   - SDWebImage (5.21.7):
     - SDWebImage/Core (= 5.21.7)
   - SDWebImage/Core (5.21.7)
@@ -76,6 +83,8 @@ PODS:
     - Flutter
 
 DEPENDENCIES:
+  - audioplayers_darwin (from `.symlinks/plugins/audioplayers_darwin/darwin`)
+  - codec2_flutter (from `.symlinks/plugins/codec2_flutter/ios`)
   - device_info_plus (from `.symlinks/plugins/device_info_plus/ios`)
   - file_picker (from `.symlinks/plugins/file_picker/ios`)
   - Flutter (from `Flutter`)
@@ -89,6 +98,7 @@ DEPENDENCIES:
   - package_info_plus (from `.symlinks/plugins/package_info_plus/ios`)
   - path_provider_foundation (from `.symlinks/plugins/path_provider_foundation/darwin`)
   - permission_handler_apple (from `.symlinks/plugins/permission_handler_apple/ios`)
+  - record_ios (from `.symlinks/plugins/record_ios/ios`)
   - share_plus (from `.symlinks/plugins/share_plus/ios`)
   - shared_preferences_foundation (from `.symlinks/plugins/shared_preferences_foundation/darwin`)
   - url_launcher_ios (from `.symlinks/plugins/url_launcher_ios/ios`)
@@ -103,6 +113,10 @@ SPEC REPOS:
     - SwiftyGif
 
 EXTERNAL SOURCES:
+  audioplayers_darwin:
+    :path: ".symlinks/plugins/audioplayers_darwin/darwin"
+  codec2_flutter:
+    :path: ".symlinks/plugins/codec2_flutter/ios"
   device_info_plus:
     :path: ".symlinks/plugins/device_info_plus/ios"
   file_picker:
@@ -129,6 +143,8 @@ EXTERNAL SOURCES:
     :path: ".symlinks/plugins/path_provider_foundation/darwin"
   permission_handler_apple:
     :path: ".symlinks/plugins/permission_handler_apple/ios"
+  record_ios:
+    :path: ".symlinks/plugins/record_ios/ios"
   share_plus:
     :path: ".symlinks/plugins/share_plus/ios"
   shared_preferences_foundation:
@@ -139,6 +155,8 @@ EXTERNAL SOURCES:
     :path: ".symlinks/plugins/vibration/ios"
 
 SPEC CHECKSUMS:
+  audioplayers_darwin: 4f9ca89d92d3d21cec7ec580e78ca888e5fb68bd
+  codec2_flutter: 15e24fa897d9d903a2afb1cc5a17ae3ac88b6d6f
   device_info_plus: 21fcca2080fbcd348be798aa36c3e5ed849eefbe
   DKImagePickerController: 946cec48c7873164274ecc4624d19e3da4c1ef3c
   DKPhotoGallery: b3834fecb755ee09a593d7c9e389d8b5d6deed60
@@ -155,6 +173,7 @@ SPEC CHECKSUMS:
   package_info_plus: af8e2ca6888548050f16fa2f1938db7b5a5df499
   path_provider_foundation: bb55f6dbba17d0dccd6737fe6f7f34fbd0376880
   permission_handler_apple: 4ed2196e43d0651e8ff7ca3483a069d469701f2d
+  record_ios: 412daca2350b228e698fffcd08f1f94ceb1e3844
   SDWebImage: e9fc87c1aab89a8ab1bbd74eba378c6f53be8abf
   share_plus: 50da8cb520a8f0f65671c6c6a99b3617ed10a58a
   shared_preferences_foundation: 7036424c3d8ec98dfe75ff1667cb0cd531ec82bb

ios/Runner/Info.plist

@@ -66,6 +66,8 @@
 	<string>MeshCore SAR needs location access to display team members and SAR markers on the map</string>
 	<key>NSMotionUsageDescription</key>
 	<string>MeshCore SAR needs access to the compass to show your heading direction on the map</string>
+	<key>NSMicrophoneUsageDescription</key>
+	<string>MeshCore SAR needs microphone access to send voice messages over the mesh radio network during SAR operations</string>
 	<key>NSPhotoLibraryUsageDescription</key>
 	<string>MeshCore SAR may need access to your photo library to attach images to messages or save map screenshots for documentation during SAR operations</string>
 	<key>UIApplicationSceneManifest</key>