feat: fetch and cache author profiles in explore page

- Create profileService to fetch and cache kind:0 metadata
- Fetch profiles for all blog post authors on explore page
- Store profiles in event store for immediate access
- Rebroadcast profiles to local/all relays per user settings
- Fixes 'Unknown' author names by ensuring profiles are cached
- Uses mapEventsToStore to automatically populate event store

src/services/profileService.ts

@@ -0,0 +1,81 @@
+import { RelayPool, completeOnEose, onlyEvents, mapEventsToStore } from 'applesauce-relay'
+import { lastValueFrom, merge, Observable, takeUntil, timer, toArray } from 'rxjs'
+import { NostrEvent } from 'nostr-tools'
+import { IEventStore } from 'applesauce-core'
+import { prioritizeLocalRelays, partitionRelays } from '../utils/helpers'
+import { rebroadcastEvents } from './rebroadcastService'
+import { UserSettings } from './settingsService'
+
+/**
+ * Fetches profile metadata (kind:0) for a list of pubkeys
+ * Stores profiles in the event store and optionally to local relays
+ */
+export const fetchProfiles = async (
+  relayPool: RelayPool,
+  eventStore: IEventStore,
+  pubkeys: string[],
+  settings?: UserSettings
+): Promise<NostrEvent[]> => {
+  try {
+    if (pubkeys.length === 0) {
+      return []
+    }
+
+    const uniquePubkeys = Array.from(new Set(pubkeys))
+    console.log('👤 Fetching profiles (kind:0) for', uniquePubkeys.length, 'authors')
+
+    const relayUrls = Array.from(relayPool.relays.values()).map(relay => relay.url)
+    const prioritized = prioritizeLocalRelays(relayUrls)
+    const { local: localRelays, remote: remoteRelays } = partitionRelays(prioritized)
+
+    // Keep only the most recent profile for each pubkey
+    const profilesByPubkey = new Map<string, NostrEvent>()
+
+    const processEvent = (event: NostrEvent) => {
+      const existing = profilesByPubkey.get(event.pubkey)
+      if (!existing || event.created_at > existing.created_at) {
+        profilesByPubkey.set(event.pubkey, event)
+      }
+    }
+
+    const local$ = localRelays.length > 0
+      ? relayPool
+          .req(localRelays, { kinds: [0], authors: uniquePubkeys })
+          .pipe(
+            onlyEvents(),
+            completeOnEose(),
+            takeUntil(timer(1200)),
+            mapEventsToStore(eventStore)
+          )
+      : new Observable<NostrEvent>((sub) => sub.complete())
+
+    const remote$ = remoteRelays.length > 0
+      ? relayPool
+          .req(remoteRelays, { kinds: [0], authors: uniquePubkeys })
+          .pipe(
+            onlyEvents(),
+            completeOnEose(),
+            takeUntil(timer(6000)),
+            mapEventsToStore(eventStore)
+          )
+      : new Observable<NostrEvent>((sub) => sub.complete())
+
+    const events = await lastValueFrom(merge(local$, remote$).pipe(toArray()))
+    
+    events.forEach(processEvent)
+
+    const profiles = Array.from(profilesByPubkey.values())
+    console.log('✅ Fetched', profiles.length, 'unique profiles')
+
+    // Rebroadcast profiles to local/all relays based on settings
+    if (profiles.length > 0) {
+      await rebroadcastEvents(profiles, relayPool, settings)
+    }
+
+    return profiles
+  } catch (error) {
+    console.error('Failed to fetch profiles:', error)
+    return []
+  }
+}
+