Fix scan_type migration: add process.exit() for standalone execution

run-all.js executes each migration as a child process via node. The migration
must call process.exit() or the pool keeps it alive and the runner times out
(exit code null).

backend/migrations/add_ivanti_findings_scan_type.js

@@ -5,7 +5,7 @@
 
 const pool = require('../db');
 
-async function up() {
+async function run() {
     await pool.query(`
         ALTER TABLE ivanti_findings
         ADD COLUMN IF NOT EXISTS scan_type VARCHAR(20) DEFAULT NULL
@@ -13,4 +13,11 @@ async function up() {
     console.log('[Migration] Added scan_type column to ivanti_findings');
 }
 
-module.exports = { up };
+module.exports = { run };
+
+if (require.main === module) {
+    run().then(() => process.exit(0)).catch((err) => {
+        console.error('Migration failed:', err.message);
+        process.exit(1);
+    });
+}