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

lib/screens/contacts_screen.dart

@@ -1244,8 +1244,9 @@ class _ContactsScreenState extends State<ContactsScreen>
                     ? Text(context.l10n.contacts_pathTrace)
                     : Text(context.l10n.contacts_ping),
                 onTap: () {
-                  final hw =
-                      context.read<MeshCoreConnector>().pathHashByteWidth;
+                  final hw = context
+                      .read<MeshCoreConnector>()
+                      .pathHashByteWidth;
                   Navigator.push(
                     context,
                     MaterialPageRoute(
@@ -1277,8 +1278,9 @@ class _ContactsScreenState extends State<ContactsScreen>
                     ? Text(context.l10n.contacts_pathTrace)
                     : Text(context.l10n.contacts_ping),
                 onTap: () {
-                  final hw =
-                      context.read<MeshCoreConnector>().pathHashByteWidth;
+                  final hw = context
+                      .read<MeshCoreConnector>()
+                      .pathHashByteWidth;
                   Navigator.push(
                     context,
                     MaterialPageRoute(
@@ -1324,8 +1326,9 @@ class _ContactsScreenState extends State<ContactsScreen>
                   leading: const Icon(Icons.radar, color: Colors.green),
                   title: Text(context.l10n.contacts_chatTraceRoute),
                   onTap: () {
-                    final hw =
-                        context.read<MeshCoreConnector>().pathHashByteWidth;
+                    final hw = context
+                        .read<MeshCoreConnector>()
+                        .pathHashByteWidth;
                     Navigator.push(
                       context,
                       MaterialPageRoute(