Add companion radio stats, adaptive backoff, path hash width, and UI improvements

- Companion radio stats: poll and display noise floor, RSSI, SNR, airtime
  with dedicated ValueNotifier and ref-counted polling
- Adaptive RF-aware TX backoff based on radio conditions instead of fixed 5s
- Variable-width path hash support (1-3 bytes per hop)
- Air activity dot indicator in app bar with tap to open stats screen
- Jump to oldest unread setting for chat screens
- 1s send cooldown on DM and channel messages
- Link style: theme-aware orange, added EmailLinkifier
- New languages: Hungarian, Japanese, Korean
- Remove dead DeviceScreen and BatteryIndicatorChip
- Remove wakelock_plus dependency
- TX power fields now read as signed int8

macos/Flutter/GeneratedPluginRegistrant.swift

@@ -9,7 +9,6 @@ import flutter_blue_plus_darwin
 import flutter_local_notifications
 import mobile_scanner
 import package_info_plus
-import path_provider_foundation
 import share_plus
 import shared_preferences_foundation
 import sqflite_darwin
@@ -20,7 +19,6 @@ func RegisterGeneratedPlugins(registry: FlutterPluginRegistry) {
   FlutterLocalNotificationsPlugin.register(with: registry.registrar(forPlugin: "FlutterLocalNotificationsPlugin"))
   MobileScannerPlugin.register(with: registry.registrar(forPlugin: "MobileScannerPlugin"))
   FPPPackageInfoPlusPlugin.register(with: registry.registrar(forPlugin: "FPPPackageInfoPlusPlugin"))
-  PathProviderPlugin.register(with: registry.registrar(forPlugin: "PathProviderPlugin"))
   SharePlusMacosPlugin.register(with: registry.registrar(forPlugin: "SharePlusMacosPlugin"))
   SharedPreferencesPlugin.register(with: registry.registrar(forPlugin: "SharedPreferencesPlugin"))
   SqflitePlugin.register(with: registry.registrar(forPlugin: "SqflitePlugin"))