Add advanced path management, debug logging, and fix channel sync

New features:
- In-app debug log viewer with copy/clear functionality
- Advanced path management UI with history and custom path builder
- Battery indicator widget with voltage/percentage toggle
- Contact/channel filtering and sorting improvements
- Repeater command ACK tracking with path history integration

Fixes:
- Switch channel sync from parallel to sequential to prevent timeouts
- Preserve path overrides when contacts refresh from device
- Fix ACK hash computation for SMAZ-encoded messages
- Proper cleanup of pending operations on disconnect

lib/connector/meshcore_protocol.dart

@@ -592,16 +592,18 @@ Uint8List buildSendCliCommandFrame(
   Uint8List repeaterPubKey,
   String command, {
   int attempt = 0,
+  int? timestampSeconds,
 }) {
   final textBytes = utf8.encode(command);
-  final timestamp = DateTime.now().millisecondsSinceEpoch ~/ 1000;
+  final timestamp = timestampSeconds ?? (DateTime.now().millisecondsSinceEpoch ~/ 1000);
   const prefixSize = 6;
+  final safeAttempt = attempt.clamp(0, 3);
   final frame = Uint8List(1 + 1 + 1 + 4 + prefixSize + textBytes.length + 1);
   int offset = 0;
 
   frame[offset++] = cmdSendTxtMsg;
   frame[offset++] = txtTypeCliData;
-  frame[offset++] = attempt & 0xFF;
+  frame[offset++] = safeAttempt;
   writeUint32LE(frame, offset, timestamp);
   offset += 4;