Add web UI for SSH CA, Transit, and User engines; full security audit and remediation

Web UI: Added browser-based management for all three remaining engines
(SSH CA, Transit, User E2E). Includes gRPC client wiring, handler files,
7 HTML templates, dashboard mount forms, and conditional navigation links.
Fixed REST API routes to match design specs (SSH CA cert singular paths,
Transit PATCH for update-key-config).

Security audit: Conducted full-system audit covering crypto core, all
engine implementations, API servers, policy engine, auth, deployment,
and documentation. Identified 42 new findings (#39-#80) across all
severity levels.

Remediation of all 8 High findings:
- #68: Replaced 14 JSON-injection-vulnerable error responses with safe
  json.Encoder via writeJSONError helper
- #48: Added two-layer path traversal defense (barrier validatePath
  rejects ".." segments; engine ValidateName enforces safe name pattern)
- #39: Extended RLock through entire crypto operations in barrier
  Get/Put/Delete/List to eliminate TOCTOU race with Seal
- #40: Unified ReWrapKeys and seal_config UPDATE into single SQLite
  transaction to prevent irrecoverable data loss on crash during MEK
  rotation
- #49: Added resolveTTL to CA engine enforcing issuer MaxTTL ceiling
  on handleIssue and handleSignCSR
- #61: Store raw ECDH private key bytes in userState for effective
  zeroization on Seal
- #62: Fixed user engine policy resource path from mountPath to
  mountName() so policy rules match correctly
- #69: Added newPolicyChecker helper and passed service-level policy
  evaluation to all 25 typed REST handler engine.Request structs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/webserver/cert_detail_test.go

@@ -124,6 +124,120 @@ func (m *mockVault) CreatePolicy(ctx context.Context, token string, rule PolicyR
 
 func (m *mockVault) DeletePolicy(ctx context.Context, token, id string) error { return nil }
 
+// SSH CA stubs
+func (m *mockVault) GetSSHCAPublicKey(ctx context.Context, mount string) (*SSHCAPublicKey, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) SSHCASignHost(ctx context.Context, token, mount string, req SSHCASignRequest) (*SSHCASignResult, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) SSHCASignUser(ctx context.Context, token, mount string, req SSHCASignRequest) (*SSHCASignResult, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) ListSSHCAProfiles(ctx context.Context, token, mount string) ([]SSHCAProfileSummary, error) {
+	return nil, nil
+}
+func (m *mockVault) GetSSHCAProfile(ctx context.Context, token, mount, name string) (*SSHCAProfile, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) CreateSSHCAProfile(ctx context.Context, token, mount string, req SSHCAProfileRequest) error {
+	return nil
+}
+func (m *mockVault) UpdateSSHCAProfile(ctx context.Context, token, mount, name string, req SSHCAProfileRequest) error {
+	return nil
+}
+func (m *mockVault) DeleteSSHCAProfile(ctx context.Context, token, mount, name string) error {
+	return nil
+}
+func (m *mockVault) ListSSHCACerts(ctx context.Context, token, mount string) ([]SSHCACertSummary, error) {
+	return nil, nil
+}
+func (m *mockVault) GetSSHCACert(ctx context.Context, token, mount, serial string) (*SSHCACertDetail, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) RevokeSSHCACert(ctx context.Context, token, mount, serial string) error {
+	return nil
+}
+func (m *mockVault) DeleteSSHCACert(ctx context.Context, token, mount, serial string) error {
+	return nil
+}
+func (m *mockVault) GetSSHCAKRL(ctx context.Context, mount string) ([]byte, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+
+// Transit stubs
+func (m *mockVault) ListTransitKeys(ctx context.Context, token, mount string) ([]TransitKeySummary, error) {
+	return nil, nil
+}
+func (m *mockVault) GetTransitKey(ctx context.Context, token, mount, name string) (*TransitKeyDetail, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) CreateTransitKey(ctx context.Context, token, mount, name, keyType string) error {
+	return nil
+}
+func (m *mockVault) DeleteTransitKey(ctx context.Context, token, mount, name string) error {
+	return nil
+}
+func (m *mockVault) RotateTransitKey(ctx context.Context, token, mount, name string) error {
+	return nil
+}
+func (m *mockVault) UpdateTransitKeyConfig(ctx context.Context, token, mount, name string, minDecryptVersion int, allowDeletion bool) error {
+	return nil
+}
+func (m *mockVault) TrimTransitKey(ctx context.Context, token, mount, name string) (int, error) {
+	return 0, nil
+}
+func (m *mockVault) TransitEncrypt(ctx context.Context, token, mount, key, plaintext, transitCtx string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) TransitDecrypt(ctx context.Context, token, mount, key, ciphertext, transitCtx string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) TransitRewrap(ctx context.Context, token, mount, key, ciphertext, transitCtx string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) TransitSign(ctx context.Context, token, mount, key, input string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) TransitVerify(ctx context.Context, token, mount, key, input, signature string) (bool, error) {
+	return false, fmt.Errorf("not implemented")
+}
+func (m *mockVault) TransitHMAC(ctx context.Context, token, mount, key, input string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) GetTransitPublicKey(ctx context.Context, token, mount, name string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+
+// User stubs
+func (m *mockVault) UserRegister(ctx context.Context, token, mount string) (*UserKeyInfo, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) UserProvision(ctx context.Context, token, mount, username string) (*UserKeyInfo, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) GetUserPublicKey(ctx context.Context, token, mount, username string) (*UserKeyInfo, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) ListUsers(ctx context.Context, token, mount string) ([]string, error) {
+	return nil, nil
+}
+func (m *mockVault) UserEncrypt(ctx context.Context, token, mount, plaintext, metadata string, recipients []string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) UserDecrypt(ctx context.Context, token, mount, envelope string) (*UserDecryptResult, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) UserReEncrypt(ctx context.Context, token, mount, envelope string) (string, error) {
+	return "", fmt.Errorf("not implemented")
+}
+func (m *mockVault) UserRotateKey(ctx context.Context, token, mount string) (*UserKeyInfo, error) {
+	return nil, fmt.Errorf("not implemented")
+}
+func (m *mockVault) UserDeleteUser(ctx context.Context, token, mount, username string) error {
+	return nil
+}
+
 func (m *mockVault) Close() error { return nil }
 
 // ---- handleTGZDownload tests ----