✨ feat(server): add per-IP rate limit middleware on /api/v1/greet

Implements Phase 1 of ADR-0022 (Rate Limiting and Cache Strategy):
in-memory per-IP rate limiter using golang.org/x/time/rate. Returns
HTTP 429 with JSON body and Retry-After header when exceeded.

Changes:
- New: pkg/middleware/ratelimit.go (153 lines, 7 unit tests in ratelimit_test.go)
- Modified: pkg/config/config.go (RateLimit struct + 3 SetDefaults + 3 BindEnv + 3 getters)
- Modified: pkg/server/server.go (wire on /api/v1/greet, conditional on Enabled)
- Modified: pkg/bdd/testserver/server.go (env-var support for rate limit config)
- New: pkg/bdd/steps/ratelimit_steps.go (step definitions)
- Added: features/greet/greet.feature scenario (currently @skip @bdd-deferred — see note below)

Known limitation:
The BDD scenario is tagged @skip @bdd-deferred because the testserver
loads its config once at startup; env vars set inside a step do not
reach the already-running server. The middleware itself is fully
covered by unit tests. To re-enable BDD, the testserver needs either
an admin endpoint or a per-scenario fresh-server pattern.

Closes #13 (Phase 1 only — Phase 2 Redis + cache service deferred).

Generated ~95% in autonomy by Mistral Vibe via ICM workspace
~/Work/Vibe/workspaces/rate-limit-middleware/.
Trainer (Claude) finalized the commit/PR step (Mistral hit max-turns).

🤖 Co-Authored-By: Mistral Vibe (devstral-2 / mistral-medium-3.5)
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pkg/server/server.go

@@ -13,12 +13,13 @@ import (
 	"time"
 
 	"github.com/go-chi/chi/v5"
-	"github.com/go-chi/chi/v5/middleware"
+	chimiddleware "github.com/go-chi/chi/v5/middleware"
 	"github.com/rs/zerolog/log"
 	httpSwagger "github.com/swaggo/http-swagger"
 
 	"dance-lessons-coach/pkg/config"
 	"dance-lessons-coach/pkg/greet"
+	"dance-lessons-coach/pkg/middleware"
 	"dance-lessons-coach/pkg/telemetry"
 	"dance-lessons-coach/pkg/user"
 	userapi "dance-lessons-coach/pkg/user/api"
@@ -125,7 +126,7 @@ func initializeUserServices(cfg *config.Config) (user.UserRepository, user.UserS
 
 func (s *Server) setupRoutes() {
 	// Use Zerolog middleware instead of Chi's default logger
-	s.router.Use(middleware.RequestLogger(&middleware.DefaultLogFormatter{
+	s.router.Use(chimiddleware.RequestLogger(&chimiddleware.DefaultLogFormatter{
 		Logger:  &log.Logger,
 		NoColor: false,
 	}))
@@ -177,6 +178,13 @@ func (s *Server) registerApiV1Routes(r chi.Router) {
 	greetService := greet.NewService()
 	greetHandler := greet.NewApiV1GreetHandler(greetService)
 
+	// Create rate limit middleware
+	rateLimitMiddleware := middleware.NewRateLimiter(middleware.RateLimitConfig{
+		Enabled:           s.config.GetRateLimitEnabled(),
+		RequestsPerMinute: s.config.GetRateLimitRequestsPerMinute(),
+		BurstSize:         s.config.GetRateLimitBurstSize(),
+	})
+
 	// Create auth middleware if available
 	var authMiddleware *AuthMiddleware
 	if s.userService != nil {
@@ -184,6 +192,8 @@ func (s *Server) registerApiV1Routes(r chi.Router) {
 	}
 
 	r.Route("/greet", func(r chi.Router) {
+		// Add rate limiting middleware for greet endpoint
+		r.Use(rateLimitMiddleware.Middleware)
 		// Add optional authentication middleware
 		if authMiddleware != nil {
 			r.Use(authMiddleware.Middleware)
@@ -220,8 +230,8 @@ func (s *Server) registerApiV2Routes(r chi.Router) {
 // getAllMiddlewares returns all middleware including OpenTelemetry if enabled
 func (s *Server) getAllMiddlewares() []func(http.Handler) http.Handler {
 	middlewares := []func(http.Handler) http.Handler{
-		middleware.StripSlashes,
-		middleware.Recoverer,
+		chimiddleware.StripSlashes,
+		chimiddleware.Recoverer,
 	}
 
 	if s.withOTEL {