Fix Build Errors (Clean up ChatComponent and useNostrChat)

- Remove unused ChatMessage interface from ChatComponent to streamline
the code.
- Update getPeerAvatar function parameter for clarity by renaming it to
_peer.
- Remove unnecessary useNostrStore import in useNostrChat, simplifying
the composable's structure.

src/composables/useNostrChat.ts

@@ -1,5 +1,5 @@
 import { ref, computed, readonly } from 'vue'
-import { useNostrStore } from '@/stores/nostr'
+
 import { SimplePool, nip04, finalizeEvent, type EventTemplate } from 'nostr-tools'
 import { hexToBytes } from '@/lib/utils/crypto'
 import { getAuthToken } from '@/lib/config/lnbits'
@@ -31,7 +31,6 @@ const getRelays = (): NostrRelayConfig[] => {
 }
 
 export function useNostrChat() {
-  const nostrStore = useNostrStore()
   
   // State
   const isConnected = ref(false)