Msg Retry fixes, channel message fixes. Notification fixes. Make more desktop friendly. Enhance retry algo. Fix predicted location clustering add retries to reactions and fix the reactions in private DMS centralize and cleanup code in var areas

lib/screens/map_screen.dart

@@ -617,19 +617,6 @@ class _MapScreenState extends State<MapScreen> {
         if (r != null) anchorSet.add(LatLng(r.latitude!, r.longitude!));
       }
 
-      // Fallback: for any last-hop byte with no GPS repeater, average the
-      // positions of contacts with known GPS that share the same last hop.
-      // Those contacts are all adjacent to the same unknown repeater, so their
-      // centroid is a reasonable proxy for its location.
-      for (final byte in lastHopBytes) {
-        if (repeaterByHash.containsKey(byte)) continue;
-        for (final c in withLocation) {
-          if (c.path.isNotEmpty && c.path.last == byte) {
-            anchorSet.add(LatLng(c.latitude!, c.longitude!));
-          }
-        }
-      }
-
       // Filter anchors that are geometrically inconsistent with radio range.
       // Two anchors more than 2 * maxRange apart cannot both be in direct radio
       // range of the same node, so isolated outliers are removed.
@@ -641,15 +628,12 @@ class _MapScreenState extends State<MapScreen> {
 
       final LatLng position;
       if (anchors.length == 1) {
-        // Offset single-anchor guesses so they don't overlap the repeater marker.
-        // Use the contact's public key byte as a deterministic angle seed.
-        const offsetDeg = 0.003; // ~330 m at the equator
-        final angle = (contact.publicKey[1] / 255.0) * 2 * pi;
-        position = LatLng(
-          anchors[0].latitude + offsetDeg * cos(angle),
-          anchors[0].longitude + offsetDeg * sin(angle),
+        // Spread single-anchor guesses around the anchor so they remain visible.
+        position = _offsetGuessedPosition(
+          anchors[0],
+          contact,
+          radiusMeters: 330,
         );
-
         if (!_checkLocationPlausibility(
           position.latitude,
           position.longitude,
@@ -662,7 +646,11 @@ class _MapScreenState extends State<MapScreen> {
           lat += a.latitude;
           lon += a.longitude;
         }
-        position = LatLng(lat / anchors.length, lon / anchors.length);
+        position = _offsetGuessedPosition(
+          LatLng(lat / anchors.length, lon / anchors.length),
+          contact,
+          radiusMeters: anchors.length >= 3 ? 80 : 120,
+        );
         if (!_checkLocationPlausibility(
           position.latitude,
           position.longitude,
@@ -682,6 +670,31 @@ class _MapScreenState extends State<MapScreen> {
     return result;
   }
 
+  LatLng _offsetGuessedPosition(
+    LatLng anchor,
+    Contact contact, {
+    required double radiusMeters,
+  }) {
+    final seed = _guessSeed(contact.publicKey);
+    final angle = ((seed & 0xFFFF) / 0x10000) * 2 * pi;
+    final latOffsetDeg = (radiusMeters / 111320.0) * cos(angle);
+    final lonScale = max(cos(anchor.latitude * pi / 180.0).abs(), 0.2);
+    final lonOffsetDeg = (radiusMeters / (111320.0 * lonScale)) * sin(angle);
+    return LatLng(
+      anchor.latitude + latOffsetDeg,
+      anchor.longitude + lonOffsetDeg,
+    );
+  }
+
+  int _guessSeed(Uint8List publicKey) {
+    var seed = 0x811C9DC5;
+    for (final byte in publicKey) {
+      seed ^= byte;
+      seed = (seed * 0x01000193) & 0x7FFFFFFF;
+    }
+    return seed;
+  }
+
   /// Estimates the free-space maximum LoRa range in km from the connected
   /// device's current radio parameters.  Returns null if parameters are unknown.
   double? _estimateLoRaRangeKm(MeshCoreConnector connector) {