Multibyte: some path fixes

- Validate encoded path hop counts before saving or sending custom paths
- Fix multi-byte path reversal by reversing hops instead of raw bytes
- Decode raw log path lengths using packed path_len format
- Localize path hash mode options and optimize map anchor lookup

lib/screens/map_screen.dart

@@ -700,6 +700,16 @@ class _MapScreenState extends State<MapScreen> {
     int pathHashByteWidth,
   ) {
     final result = <_GuessedLocation>[];
+    final hopWidth = pathHashByteWidth.clamp(1, 4).toInt();
+    final anchorsByPrefix = <String, List<Contact>>{};
+    for (final repeater in withLocation) {
+      if (repeater.type != advTypeRepeater) continue;
+      if (repeater.publicKey.length < hopWidth) continue;
+      final prefix = PathHelper.formatHopHex(
+        repeater.publicKey.sublist(0, hopWidth),
+      );
+      anchorsByPrefix.putIfAbsent(prefix, () => []).add(repeater);
+    }
 
     for (final contact in allContacts) {
       if (contact.hasLocation) continue;
@@ -722,21 +732,13 @@ class _MapScreenState extends State<MapScreen> {
       ];
       for (final pathBytes in pathSets) {
         if (pathBytes.isEmpty) continue;
-        final hopWidth = pathHashByteWidth.clamp(1, 4);
         final lastHop = pathBytes.sublist(max(0, pathBytes.length - hopWidth));
         if (lastHop.isEmpty) continue;
 
-        for (final repeater in withLocation) {
-          if (repeater.type != advTypeRepeater) continue;
-          if (repeater.publicKey.length < lastHop.length) continue;
-          if (!listEquals(
-            repeater.publicKey.sublist(0, lastHop.length),
-            lastHop,
-          )) {
-            continue;
-          }
+        final repeaters = anchorsByPrefix[PathHelper.formatHopHex(lastHop)];
+        if (repeaters != null && repeaters.isNotEmpty) {
+          final repeater = repeaters.first;
           anchorSet.add(LatLng(repeater.latitude!, repeater.longitude!));
-          break;
         }
       }
 
@@ -2304,10 +2306,17 @@ class _MapScreenState extends State<MapScreen> {
       connector.pathHashByteWidth.clamp(1, pubKeySize),
       contact.publicKey.length,
     ).toInt();
+    final hopPrefix = contact.publicKey.sublist(0, hopWidth);
+    for (final existingHop in PathHelper.splitPathBytes(
+      _pathTrace,
+      connector.pathHashByteWidth,
+    )) {
+      if (listEquals(existingHop, hopPrefix)) {
+        return;
+      }
+    }
     setState(() {
-      _pathTrace.addAll(
-        contact.publicKey.sublist(0, hopWidth),
-      ); // Add the hop-width prefix of the public key to the trace
+      _pathTrace.addAll(hopPrefix); // Add the hop-width pubkey prefix.
       _pathTraceHopWidths.add(hopWidth);
       _pathTraceContacts.add(
         contact.copyWith(