refactor: Simplify Nostr connection management and enhance store integration

- Refactor useNostr composable to utilize a centralized Pinia store for connection state and client management.
- Update NostrFeed and App components to leverage the new store-based approach for relay configuration and client instantiation.
- Remove direct relay URL handling from components, improving maintainability and consistency across the application.

src/composables/useSocial.ts

@@ -4,8 +4,11 @@ import { createTextNote, createReaction, createProfileMetadata } from '@/lib/nos
 import { identity } from '@/composables/useIdentity'
 import { toast } from 'vue-sonner'
 
-export function useSocial(relayUrls: string[]) {
-  const client = new NostrClient({ relays: relayUrls })
+import { useNostr } from './useNostr'
+
+export function useSocial(relayUrls?: string[]) {
+  const { getClient } = useNostr(relayUrls ? { relays: relayUrls } : undefined)
+  const client = getClient()
   const isPublishing = ref(false)
   const profiles = ref(new Map<string, any>())
 
@@ -152,5 +155,4 @@ export function useSocial(relayUrls: string[]) {
 }
 
 // Export singleton instance for global use
-import { config } from '@/lib/config'
-export const social = useSocial(config.nostr.relays)
+export const social = useSocial()