Add sermon retention policy feature

Implemented a configurable retention policy system for sermons with automatic cleanup:
- Added settings table to store retention policy configuration
- Created API endpoints for getting/setting retention policy
- Added Database Settings section to admin page with retention options (forever, 1-10 years)
- Implemented manual cleanup endpoint for on-demand deletion
- Added automated daily cleanup task via Nitro plugin
- Sermons are deleted based on their date field according to the retention policy

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

server/utils/database.ts

@@ -61,6 +61,13 @@ export interface RateLimit {
   reset_at: string
 }
 
+export interface Setting {
+  id?: number
+  key: string
+  value: string
+  updated_at?: string
+}
+
 export function getDatabase() {
   if (!db) {
     const dbPath = join(process.cwd(), 'data', 'sermons.db')
@@ -147,6 +154,15 @@ export function getDatabase() {
         UNIQUE(identifier, endpoint)
       )
     `)
+
+    db.exec(`
+      CREATE TABLE IF NOT EXISTS settings (
+        id INTEGER PRIMARY KEY AUTOINCREMENT,
+        key TEXT UNIQUE NOT NULL,
+        value TEXT NOT NULL,
+        updated_at DATETIME DEFAULT CURRENT_TIMESTAMP
+      )
+    `)
     
     // Insert default admin user from environment variables with hashed password
     const config = useRuntimeConfig()
@@ -354,3 +370,32 @@ export function resetRateLimit(identifier: string, endpoint: string) {
   return db.prepare('DELETE FROM rate_limits WHERE identifier = ? AND endpoint = ?')
     .run(identifier, endpoint)
 }
+
+// Settings management functions
+export function getSetting(key: string) {
+  const db = getDatabase()
+  return db.prepare('SELECT * FROM settings WHERE key = ?').get(key) as Setting | undefined
+}
+
+export function setSetting(key: string, value: string) {
+  const db = getDatabase()
+  const existing = getSetting(key)
+
+  if (existing) {
+    return db.prepare('UPDATE settings SET value = ?, updated_at = CURRENT_TIMESTAMP WHERE key = ?').run(value, key)
+  } else {
+    return db.prepare('INSERT INTO settings (key, value) VALUES (?, ?)').run(key, value)
+  }
+}
+
+// Sermon retention policy functions
+export function deleteOldSermons(retentionDays: number) {
+  const db = getDatabase()
+  // Calculate the cutoff date based on retention days
+  const cutoffDate = new Date()
+  cutoffDate.setDate(cutoffDate.getDate() - retentionDays)
+  const cutoffDateStr = cutoffDate.toISOString().split('T')[0] // Format as YYYY-MM-DD
+
+  // Delete sermons older than the cutoff date
+  return db.prepare('DELETE FROM sermons WHERE date < ?').run(cutoffDateStr)
+}