fix(11-06): send Cache-Control: no-cache, private on the jwt.auth 401

The recorded PHP 401 for a missing bearer (realtime token no-bearer
case) carries Laravel's default Cache-Control header; the Go guard's
401 omitted it, so the replay failed on header.Cache-Control.

modules/bouncer/README.md

@@ -13,7 +13,7 @@ bouncer decides who is making a request. Guards (`bouncer.Guard`, `bouncer.Crede
 - Token minting with `bouncer.Mint` (frontend audience) and `bouncer.MintAudience` (any audience), each returning the signed token and its random jti.
 - Verification with HS256 pinned and `exp` and `sub` required: `bouncer.Verify` and `bouncer.VerifyClaims` accept frontend tokens, including legacy tokens with no audience claim; `bouncer.VerifyClaimsAudience` requires an explicit audience, so a backend token cannot pass a frontend check and the other way round.
 - Refresh with `bouncer.Refresh`, `bouncer.RefreshAudience` and `bouncer.RefreshAudienceFor`: an expired token can be reissued while its `iat` is inside the refresh window; the old jti is blacklisted after a grace period. `bouncer.RefreshAudienceFor` also reloads the user and refuses deleted users and tokens issued before `bouncer.Principal.TokensValidAfter`, reporting `bouncer.ErrSubjectRejected`.
-- JWT guards: `bouncer.NewJWTGuard` (frontend) and `bouncer.NewBackendJWTGuard` (admin audience, optional custom 401 writer) read the bearer token first and then any configured cookies, load the user through a `bouncer.UserProvider`, check the blacklist and the `bouncer.Principal.TokensValidAfter` cutoff, and write a JSON 401 body (`{"error":true,"message":...}`) on failure.
+- JWT guards: `bouncer.NewJWTGuard` (frontend) and `bouncer.NewBackendJWTGuard` (admin audience, optional custom 401 writer) read the bearer token first and then any configured cookies, load the user through a `bouncer.UserProvider`, check the blacklist and the `bouncer.Principal.TokensValidAfter` cutoff, and write a JSON 401 body (`{"error":true,"message":...}`, with `Cache-Control: no-cache, private`) on failure.
 - Named guard registry: `bouncer.Registry.Register` accepts any `bouncer.Guard` or `bouncer.CredentialGuard`; `bouncer.Registry.Middleware` derives middleware that stores the principal (and credential, if any) on the context. Guards that do not implement `bouncer.UnauthorizedWriter` let unauthenticated requests through so later middleware can decide.
 - Standalone bearer middleware: `bouncer.Middleware`.
 - Context helpers: `bouncer.WithUser` and `bouncer.User` for the principal, `bouncer.WithCredential` and `bouncer.Credential` for the credential behind it (for example an API token record).

modules/bouncer/jwt.go

@@ -366,6 +366,9 @@ func mapJWTError(err error) error {
 
 func write401(w http.ResponseWriter, message string) {
 	w.Header().Set("Content-Type", "application/json")
+	// The reference backend (Laravel) sends this on every response, and a
+	// replayed 401 compares it.
+	w.Header().Set("Cache-Control", "no-cache, private")
 	w.WriteHeader(http.StatusUnauthorized)
 	_ = json.NewEncoder(w).Encode(map[string]any{"error": true, "message": message})
 }

modules/bouncer/jwt_test.go

@@ -99,6 +99,9 @@ func TestMiddlewareStatusBodies(t *testing.T) {
 		if rec.Header().Get("X-Hit") != "" {
 			t.Fatal("handler ran")
 		}
+		if got := rec.Header().Get("Cache-Control"); got != "no-cache, private" {
+			t.Fatalf("Cache-Control = %q", got)
+		}
 		var body map[string]any
 		if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
 			t.Fatal(err)