Fix/geohash blocks (#483)

* fix(geo-block): enable block/unblock for geohash users and enforce blocks\n\n- Add persisted set of blocked Nostr pubkeys in SecureIdentityStateManager\n- Check Nostr blocks for incoming messages (public + geo DMs)\n- Prevent sending geo DMs to blocked users\n- Extend /block and /unblock to resolve geohash display names to pubkeys and act accordingly\n- Improve /block list to show geohash blocks (visible names or #suffix)

* fix(geo-block): enforce blocks on geohash public and DM receive; add block/unblock actions to geohash people list

* fix: mark handlePublicMessage as @MainActor to call isMessageBlocked safely

* ui(block): show blocked indicator (nosign icon) next to blocked peers in mesh and geohash lists

* fix(geo-block): early-drop blocked pubkeys on geohash receive; filter blocked users from participants list

* fix(geo-block): purge existing geohash messages/DMs on block; block directly from chat using Nostr sender ID when available

---------

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

bitchat/Views/GeohashPeopleList.swift

@@ -71,6 +71,15 @@ struct GeohashPeopleList: View {
                                     .foregroundColor(rowColor)
                             }
                         }
+                        // Blocked indicator for geohash users
+                        if let me = myHex, person.id != me {
+                            if viewModel.isGeohashUserBlocked(pubkeyHexLowercased: person.id) {
+                                Image(systemName: "nosign")
+                                    .font(.system(size: 10))
+                                    .foregroundColor(.red)
+                                    .help("Blocked in geochash")
+                            }
+                        }
                         Spacer()
                     }
                     .padding(.horizontal)
@@ -83,6 +92,18 @@ struct GeohashPeopleList: View {
                             onTapPerson()
                         }
                     }
+                    .contextMenu {
+                        if let me = myHex, person.id == me {
+                            EmptyView()
+                        } else {
+                            let blocked = viewModel.isGeohashUserBlocked(pubkeyHexLowercased: person.id)
+                            if blocked {
+                                Button("Unblock") { viewModel.unblockGeohashUser(pubkeyHexLowercased: person.id, displayName: person.displayName) }
+                            } else {
+                                Button("Block") { viewModel.blockGeohashUser(pubkeyHexLowercased: person.id, displayName: person.displayName) }
+                            }
+                        }
+                    }
                 }
             }
         }