Nostr refactor simplify (#390)

* fix bug

* geoDM receive works, send doesnt, and incoming message doesnt make sender appear in peer list

* fix nostr dm

* geohash dms work

* Geohash DM UI: stop mixing Nostr DM temp chats into mesh offline list; ensure geohash DM senders are added to geohash people list only. Removed nostr_* sidebar append in PeopleSection; kept 64-hex mesh offline favorites. Verified build.

* refactor

* nice

* works

* merging nostr -> mesh works

* tripple click to delete all

* fix sidebar icon

* remove hash

* dms have correct recipient

* works

* wip unread badge

* geohash dms wip

* dms work

app/src/main/java/com/bitchat/android/nostr/GeohashAliasRegistry.kt

@@ -0,0 +1,24 @@
+package com.bitchat.android.nostr
+
+import java.util.concurrent.ConcurrentHashMap
+
+/**
+ * GeohashAliasRegistry
+ * - Global, thread-safe registry for alias->Nostr pubkey mappings (e.g., nostr_<pub16> -> pubkeyHex)
+ * - Allows non-UI components (e.g., MessageRouter) to resolve geohash DM aliases without depending on UI ViewModels
+ */
+object GeohashAliasRegistry {
+    private val map: MutableMap<String, String> = ConcurrentHashMap()
+
+    fun put(alias: String, pubkeyHex: String) {
+        map[alias] = pubkeyHex
+    }
+
+    fun get(alias: String): String? = map[alias]
+
+    fun contains(alias: String): Boolean = map.containsKey(alias)
+
+    fun snapshot(): Map<String, String> = HashMap(map)
+
+    fun clear() { map.clear() }
+}