UI: diversify peer colors; smarter geo notifications; 21m live location (#531)

- Use minimal-distance hue palette for mesh and geohash lists; align chat sender colors with list palette.
- Add foreground geo notifications for different channels; deep-link to bitchat://geohash/<gh>; per-geohash 60s cooldown; respect self/blocks.
- Global geohash sampling runs outside the sheet; delegate handles deeplinks and suppresses when already in-channel.
- Switch location channel sheet to continuous CoreLocation with 21m distance filter; add config knob.
- Only link geohash hashtags when standalone (no @name#abcd or word#abcd).
- Include mesh-reachable peers in mesh counts and in "bitchatters nearby" notification.
- Add TransportConfig knobs for palette and geo notifications.

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/Views/LocationChannelsSheet.swift

@@ -83,24 +83,17 @@ struct LocationChannelsSheet: View {
             }
             // Begin periodic refresh while sheet is open
             manager.beginLiveRefresh()
-            // Begin multi-channel sampling for counts
-            let ghs = manager.availableChannels.map { $0.geohash }
-            viewModel.beginGeohashSampling(for: ghs)
+            // Geohash sampling is now managed by ChatViewModel globally
         }
         .onDisappear {
             manager.endLiveRefresh()
-            viewModel.endGeohashSampling()
         }
         .onChange(of: manager.permissionState) { newValue in
             if newValue == LocationChannelManager.PermissionState.authorized {
                 manager.refreshChannels()
             }
         }
-        .onChange(of: manager.availableChannels) { newValue in
-            // Keep sampling list in sync with available channels as they refresh live
-            let ghs = newValue.map { $0.geohash }
-            viewModel.beginGeohashSampling(for: ghs)
-        }
+        .onChange(of: manager.availableChannels) { _ in }
     }
 
     private var channelList: some View {
@@ -289,9 +282,10 @@ struct LocationChannelsSheet: View {
     }
 
     private func meshCount() -> Int {
+        // Count mesh-connected OR mesh-reachable peers (exclude self)
         let myID = viewModel.meshService.myPeerID
         return viewModel.allPeers.reduce(0) { acc, peer in
-            if peer.id != myID && peer.isConnected { return acc + 1 }
+            if peer.id != myID && (peer.isConnected || peer.isReachable) { return acc + 1 }
             return acc
         }
     }