feat(openapi): move spec to a module and add a route-drift guard

[Jagadeeshftw]

Summary

The GET /api/v1/openapi.json handler previously returned a hand-written inline literal that omitted /api/v1/config. This moves the spec into a dedicated, typed module and adds a guard so docs can never silently drift from the routes.

• New src/openapi.ts exports a typed openApiSpec const (openapi: "3.0.3", existing info, complete paths). All previously-empty {} operation objects now carry real summary strings, and the missing /api/v1/config (get/patch) path is added.
• src/index.ts imports the module; the handler now does res.json(openApiSpec).
• src/__tests__/openapi.test.ts asserts openapi === "3.0.3" and info.version === "1.0.0", plus a route-drift guard: it walks the Express router stack, converts :param → {param}, and asserts every registered /api/v1/... path (skipping /health and /api/v1/openapi.json) is a key in the spec.
• README documents the spec module and drift guard.

Closes #79

Tests

PASS src/__tests__/openapi.test.ts
Tests:       3 passed, 3 total

Security notes: No new attack surface; the handler serves a static documentation object and the drift guard only reads route metadata in tests.

[mikewheeleer]

good move putting the OpenAPI spec in a module with validation. lgtm 🙌