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>

backend/test/jest-e2e.json

@@ -0,0 +1,10 @@
+{
+  "moduleFileExtensions": ["js", "json", "ts"],
+  "rootDir": ".",
+  "testEnvironment": "node",
+  "testRegex": ".e2e-spec.ts$",
+  "transform": {
+    "^.+\\.(t|j)s$": "ts-jest"
+  },
+  "setupFilesAfterEnv": ["<rootDir>/../src/test-setup.ts"]
+}