Add auto-migration for OCR settings column

🔄 Database Auto-Migration:
- Add automatic schema update in user preferences API
- Ensures ocr_settings column exists when first accessed
- Uses ADD COLUMN IF NOT EXISTS for safe migration
- Handles case where column might already exist
- No need for separate migration endpoint

This ensures the settings page will work immediately after deployment
without requiring manual database updates.

api/user/preferences.js

@@ -30,6 +30,23 @@ export default async function handler(req, res) {
   try {
     const user = verifyAuth(req);
 
+    // Ensure ocr_settings column exists (auto-migration)
+    try {
+      await client.query(`
+        ALTER TABLE user_preferences 
+        ADD COLUMN IF NOT EXISTS ocr_settings JSONB DEFAULT '{
+          "preferred_service": "openai",
+          "openai_api_key": "",
+          "ollama_url": "http://localhost:11434",
+          "auto_add_to_collection": false,
+          "confidence_threshold": 80
+        }'::jsonb;
+      `);
+    } catch (error) {
+      // Column might already exist, ignore error
+      console.log('OCR settings column may already exist:', error.message);
+    }
+
     if (req.method === 'GET') {
       // Get user preferences
       const result = await client.query(`