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/NostrSubscriptionManager.kt

@@ -0,0 +1,38 @@
+package com.bitchat.android.nostr
+
+import android.app.Application
+import android.util.Log
+import kotlinx.coroutines.CoroutineScope
+import kotlinx.coroutines.launch
+
+/**
+ * NostrSubscriptionManager
+ * - Encapsulates subscription lifecycle with NostrRelayManager
+ */
+class NostrSubscriptionManager(
+    private val application: Application,
+    private val scope: CoroutineScope
+) {
+    companion object { private const val TAG = "NostrSubscriptionManager" }
+
+    private val relayManager get() = NostrRelayManager.getInstance(application)
+
+    fun connect() = scope.launch { runCatching { relayManager.connect() }.onFailure { Log.e(TAG, "connect failed: ${it.message}") } }
+    fun disconnect() = scope.launch { runCatching { relayManager.disconnect() }.onFailure { Log.e(TAG, "disconnect failed: ${it.message}") } }
+
+    fun subscribeGiftWraps(pubkey: String, sinceMs: Long, id: String, handler: (NostrEvent) -> Unit) {
+        scope.launch {
+            val filter = NostrFilter.giftWrapsFor(pubkey, sinceMs)
+            relayManager.subscribe(filter, id, handler)
+        }
+    }
+
+    fun subscribeGeohash(geohash: String, sinceMs: Long, limit: Int, id: String, handler: (NostrEvent) -> Unit) {
+        scope.launch {
+            val filter = NostrFilter.geohashEphemeral(geohash, sinceMs, limit)
+            relayManager.subscribeForGeohash(geohash, filter, id, handler, includeDefaults = false, nRelays = 5)
+        }
+    }
+
+    fun unsubscribe(id: String) { scope.launch { runCatching { relayManager.unsubscribe(id) } } }
+}