Harden platform security, reliability, and CI after full audit.

Close deployment IDOR and gate stub payment endpoints, add production
secret validation, health probes, Redis-backed build progress, GitHub
Actions CI, expanded tests, billing/k8s refactors, and ops runbooks.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/eslint.config.mjs

@@ -0,0 +1,15 @@
+import { dirname } from 'path';
+import { fileURLToPath } from 'url';
+import { FlatCompat } from '@eslint/eslintrc';
+
+const compat = new FlatCompat({
+  baseDirectory: dirname(fileURLToPath(import.meta.url)),
+});
+
+/** @type {import('eslint').Linter.Config[]} */
+export default [
+  {
+    ignores: ['.next/**', 'node_modules/**'],
+  },
+  ...compat.extends('next/core-web-vitals', 'next/typescript'),
+];