chore: relocate backend into apps/api ahead of monorepo merge

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

apps/api/database/migrations/20270101000076-add-assets-transcode-status.js

@@ -0,0 +1,43 @@
+'use strict';
+
+// Tracks background container-remux jobs for video assets uploaded as .mov/
+// .mkv — those formats often load slowly in-browser (moov/Cues index at the
+// end of the file) compared to faststart .mp4. See services/ffmpeg.service.js
+// + services/assetTranscode.service.js.
+//
+// STRING + explicit CHECK instead of a real ENUM — same CockroachDB
+// constraint noted in 20270101000032-create-advertisements.js (addColumn
+// can't create a new enum type the way createTable can).
+module.exports = {
+  async up(queryInterface, Sequelize) {
+    await queryInterface.addColumn('assets', 'transcode_status', {
+      type: Sequelize.STRING(20),
+      allowNull: false,
+      defaultValue: 'none',
+    });
+
+    await queryInterface.addColumn('assets', 'transcode_error', {
+      type: Sequelize.TEXT,
+      allowNull: true,
+    });
+
+    await queryInterface.addConstraint('assets', {
+      fields: ['transcode_status'],
+      type: 'check',
+      name: 'check_assets_transcode_status',
+      where: { transcode_status: { [Sequelize.Op.in]: ['none', 'pending', 'processing', 'done', 'failed'] } },
+    });
+
+    await queryInterface.sequelize.query(`
+      CREATE INDEX idx_assets_transcode_status
+      ON assets (transcode_status)
+      WHERE transcode_status IN ('pending', 'processing');
+    `);
+  },
+
+  async down(queryInterface) {
+    await queryInterface.removeConstraint('assets', 'check_assets_transcode_status');
+    await queryInterface.removeColumn('assets', 'transcode_status');
+    await queryInterface.removeColumn('assets', 'transcode_error');
+  },
+};