feat: Implement push notification system for admin announcements

- Add a notification manager to handle push notifications and integrate with Nostr events.
- Create a push notification service to manage subscription and permission requests.
- Introduce components for notification settings and permission prompts in the UI.
- Update Nostr store to manage push notification state and enable/disable functionality.
- Enhance NostrFeed to send notifications for new admin announcements.
- Implement test notification functionality for development purposes.

src/lib/nostr/client.ts

@@ -1,5 +1,5 @@
-import { SimplePool, type Filter, type Event, type UnsignedEvent } from 'nostr-tools'
-import { extractReactions, extractReplyCounts, getReplyInfo, EventKinds } from './events'
+import { SimplePool, type Filter, type Event } from 'nostr-tools'
+import { getReplyInfo, EventKinds } from './events'
 
 export interface NostrClientConfig {
   relays: string[]
@@ -61,7 +61,6 @@ export class NostrClient {
   } = {}): Promise<NostrNote[]> {
     const { 
       limit = 20, 
-      since = Math.floor((Date.now() - 7 * 24 * 60 * 60 * 1000) / 1000), // Last 7 days
       authors,
       includeReplies = false
     } = options
@@ -135,7 +134,7 @@ export class NostrClient {
   /**
    * Publish an event to all connected relays
    */
-  async publishEvent(event: UnsignedEvent): Promise<void> {
+  async publishEvent(event: Event): Promise<void> {
     if (!this._isConnected) {
       throw new Error('Not connected to any relays')
     }

src/lib/nostr/identity.ts

@@ -1,5 +1,5 @@
 import { generateSecretKey, getPublicKey, nip19 } from 'nostr-tools'
-import { SecureStorage, type EncryptedData } from '@/lib/crypto/encryption'
+import { SecureStorage } from '@/lib/crypto/encryption'
 import { bytesToHex, hexToBytes } from '@/lib/utils/crypto'
 
 export interface NostrIdentity {