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/plugins/sermon-cleanup.ts

@@ -0,0 +1,56 @@
+import { getSetting, deleteOldSermons } from '../utils/database'
+
+// Map retention policy to days
+const retentionDaysMap: Record<string, number> = {
+  'forever': 0,
+  '1_month': 30,
+  '3_months': 90,
+  '6_months': 180,
+  '1_year': 365,
+  '3_years': 1095,
+  '5_years': 1825,
+  '10_years': 3650
+}
+
+async function runCleanup() {
+  try {
+    // Get the retention policy setting
+    const setting = getSetting('sermon_retention_policy')
+    const retentionPolicy = setting ? setting.value : 'forever'
+
+    const retentionDays = retentionDaysMap[retentionPolicy] || 0
+
+    if (retentionDays === 0) {
+      console.log('[Sermon Cleanup] Retention policy is set to forever, skipping cleanup')
+      return
+    }
+
+    // Delete old sermons
+    const result = deleteOldSermons(retentionDays)
+
+    if (result.changes > 0) {
+      console.log(`[Sermon Cleanup] Deleted ${result.changes} sermon(s) older than ${retentionDays} days`)
+    } else {
+      console.log(`[Sermon Cleanup] No sermons to delete (policy: ${retentionPolicy})`)
+    }
+  } catch (error) {
+    console.error('[Sermon Cleanup] Error running cleanup:', error)
+  }
+}
+
+export default defineNitroPlugin((nitroApp) => {
+  console.log('[Sermon Cleanup] Scheduling daily cleanup task')
+
+  // Run cleanup once at startup (after a short delay)
+  setTimeout(async () => {
+    console.log('[Sermon Cleanup] Running initial cleanup')
+    await runCleanup()
+  }, 10000) // 10 seconds after startup
+
+  // Schedule cleanup to run daily (every 24 hours)
+  const dailyInterval = 24 * 60 * 60 * 1000 // 24 hours in milliseconds
+  setInterval(async () => {
+    console.log('[Sermon Cleanup] Running scheduled cleanup')
+    await runCleanup()
+  }, dailyInterval)
+})