[O2B-1539] Add index on QC flags to help GAQ summary computation

Add a composite index on quality_control_flags(run_number, detector_id) that proved to reduce computation time for GAQ summary by 50% on local.

Author: isaachilly

lib/database/migrations/v1/20260305110000-add-qcf-run-detector-index.js

@@ -0,0 +1,15 @@
+'use strict';
+
+/** @type {import('sequelize-cli').Migration} */
+module.exports = {
+    up: async (queryInterface) => queryInterface.sequelize.transaction(async (transaction) => {
+        await queryInterface.addIndex('quality_control_flags', {
+            name: 'quality_control_flags_run_detector_idx',
+            fields: ['run_number', 'detector_id'],
+        }, { transaction });
+    }),
+
+    down: async (queryInterface) => queryInterface.sequelize.transaction(async (transaction) => {
+        await queryInterface.removeIndex('quality_control_flags', 'quality_control_flags_run_detector_idx', { transaction });
+    }),
+};