feat(middleware): wire UserRateLimiter into AuthMiddleware (BE-SVC-002)

UserRateLimiter had been created in initMiddlewares() + stored on
config.UserRateLimiter but never mounted — dead wiring. Per-user rate
limiting was silently not running anywhere.

Applying it as a separate `v1.Use(...)` would fire *before* the JWT
auth middleware sets `user_id`, so the limiter would always skip. The
alternative (add it after every `RequireAuth()` in ~15 route files)
bloats every routes_*.go and invites forgetting.

Solution: centralise it on AuthMiddleware. After a successful
`authenticate()` in `RequireAuth`, invoke the limiter's handler. When
the limiter is nil (tests, early boot), it's a no-op.

Changes:
  - internal/middleware/auth.go
    * new field  AuthMiddleware.userRateLimiter *UserRateLimiter
    * new method AuthMiddleware.SetUserRateLimiter(url)
    * RequireAuth() flow: authenticate → presence → user rate limit
      → c.Next(). Abort surfaces as early-return without c.Next().
  - internal/config/middlewares_init.go
    * call c.AuthMiddleware.SetUserRateLimiter(c.UserRateLimiter)
      right after AuthMiddleware construction.

Behavior:
  - Authenticated requests: per-user limit enforced via Redis, with
    X-RateLimit-Limit / Remaining / Reset headers, 429 + retry-after
    on overflow. Defaults: 1000 req/min, burst 100 (env-tunable via
    USER_RATE_LIMIT_PER_MINUTE / USER_RATE_LIMIT_BURST).
  - Unauthenticated requests: RequireAuth already rejected them → the
    limiter never runs, no behavior change there.

Tests: `go test ./internal/middleware/ -short` green (33s).
`go build ./...` + `go vet ./internal/middleware/` clean.

Refs: AUDIT_REPORT.md §4.3 "UserRateLimiter configuré non wiré"
      + §9 priority #11.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

veza-backend-api/internal/config/middlewares_init.go

@@ -75,6 +75,13 @@ func (c *Config) initMiddlewares() error {
 		c.AuthMiddleware.SetPresenceService(c.PresenceService)
 	}
 
+	// BE-SVC-002: Wire per-user rate limiter into the auth middleware so it
+	// fires automatically after every successful RequireAuth on any route.
+	// Previously UserRateLimiter was created but never mounted (dead wiring).
+	if c.UserRateLimiter != nil {
+		c.AuthMiddleware.SetUserRateLimiter(c.UserRateLimiter)
+	}
+
 	return nil
 }
 

veza-backend-api/internal/middleware/auth.go

@@ -64,6 +64,7 @@ type AuthMiddleware struct {
 	presenceService   PresenceUpdater         // v0.301: Optional, updates last_seen_at on auth
 	tokenBlacklist    TokenBlacklistChecker   // VEZA-SEC-006: Optional, nil if Redis unavailable
 	twoFactorChecker  TwoFactorChecker        // SFIX-001: Optional, for MFA enforcement
+	userRateLimiter   *UserRateLimiter        // BE-SVC-002: Optional, per-user rate limiting applied post-auth
 	logger            *zap.Logger
 }
 
@@ -102,6 +103,15 @@ func (am *AuthMiddleware) SetTwoFactorChecker(tfc TwoFactorChecker) {
 	am.twoFactorChecker = tfc
 }
 
+// SetUserRateLimiter wires the per-user rate limiter so it runs automatically
+// after every successful RequireAuth / RequireAuthWithMFA call. Centralising it
+// here avoids sprinkling UserRateLimiter.Middleware() across every protected
+// route group. nil is fine — limiter simply skipped when absent.
+// (BE-SVC-002)
+func (am *AuthMiddleware) SetUserRateLimiter(url *UserRateLimiter) {
+	am.userRateLimiter = url
+}
+
 // isSessionCheckRequest returns true for GET /auth/me (or path ending with /auth/me).
 // Used to avoid WARN logs when the frontend probes session without a token (expected case).
 func isSessionCheckRequest(path string) bool {
@@ -335,16 +345,31 @@ func (am *AuthMiddleware) authenticate(c *gin.Context) (uuid.UUID, bool) {
 // RequireAuth middleware qui exige une authentification
 func (am *AuthMiddleware) RequireAuth() gin.HandlerFunc {
 	return func(c *gin.Context) {
-		if userID, ok := am.authenticate(c); ok {
+		userID, ok := am.authenticate(c)
+		if !ok {
+			return
+		}
+
 		// v0.301 Lot P1: Update presence (last_seen_at) on each authenticated request
 		if am.presenceService != nil {
 			go func() {
 				_ = am.presenceService.UpdatePresence(context.Background(), userID, "online")
 			}()
 		}
-			c.Next()
+
+		// BE-SVC-002: Per-user rate limiting runs after auth so user_id is set.
+		// Limiter writes 429 + X-RateLimit-* headers and aborts the chain if
+		// the user exceeds their window; c.Next() below only fires when
+		// the limiter lets the request through.
+		if am.userRateLimiter != nil {
+			am.userRateLimiter.Middleware()(c)
+			if c.IsAborted() {
+				return
 			}
 		}
+
+		c.Next()
+	}
 }
 
 // OptionalAuth middleware d'authentification optionnelle