fix: resolve chi route collision on /bookings path

Use direct Post with inline middleware instead of Route group to avoid
duplicate mount path panic with the existing authenticated /bookings Route.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

backend/main.go

@@ -138,11 +138,7 @@ func main() {
 		})
 
 		// Public booking endpoints (optional auth for slot reservation)
-		r.Route("/bookings", func(r chi.Router) {
-			r.Use(mw.RateLimit(30, time.Minute))
-			r.Use(mw.OptionalAuth)
-			r.Post("/reserve", bookings.ReserveSlotHandler)
-		})
+		r.With(mw.RateLimit(30, time.Minute), mw.OptionalAuth).Post("/bookings/reserve", bookings.ReserveSlotHandler)
 
 		// Authenticated users
 		r.Group(func(r chi.Router) {