fix(GRO-1544): register health endpoint at /api/health not /health

The health check was registered on `app` at `/health`, but the HTTPRoute
routes `/api/*` to the API pod. Since auth middleware protects the /api
basePath, GET /api/health fell through to authMiddleware → 401.

Now registered on `api` before auth middleware at /api/health.

Updated UAT_PLAYBOOK.md §GRO-1485 — new health endpoint path.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/index.ts

@@ -58,8 +58,8 @@ app.use(
   })
 );
 
-// Health check (no auth required)
-app.get("/health", (c) => c.json({ status: "ok" }));
+// Health check — no auth required, registered on app at full path before auth middleware
+app.get("/api/health", (c) => c.json({ status: "ok" }));
 
 // Public booking routes — no auth required, must be registered before auth middleware
 app.route("/api/book", bookRouter);