feat: move API keys storage to Postgres database instead of localStorage

backend/database.js

@@ -25,7 +25,8 @@ const initDB = async () => {
         role TEXT DEFAULT 'user',
         api_credits INTEGER DEFAULT 10,
         storage_limit_mb INTEGER DEFAULT 500,
-        is_active BOOLEAN DEFAULT false
+        is_active BOOLEAN DEFAULT false,
+        api_keys TEXT
       )
     `);
     
@@ -36,6 +37,12 @@ const initDB = async () => {
     } catch (err) {
       // Ignore if it already exists
     }
+    
+    try {
+      await client.query(`ALTER TABLE profiles ADD COLUMN api_keys TEXT`);
+    } catch (err) {
+      // Ignore if it already exists
+    }
 
     await client.query(`
       CREATE TABLE IF NOT EXISTS projects (