Add architecture docs, fix gRPC/REST API parity, project conventions

- Add ARCHITECTURE.md with full system specification
- Add Project Structure and API Sync Rule to CLAUDE.md; ignore srv/
- Fix engine.proto MountRequest missing config field
- Add pki.proto PKIService to match unauthenticated REST PKI routes

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

web/static/style.css

@@ -22,3 +22,10 @@ th { font-weight: 600; background: #f9fafb; }
 .admin-actions { margin-top: 0.5rem; }
 .admin-actions button { background: #dc2626; }
 .admin-actions button:hover { background: #b91c1c; }
+.badge-danger { background: #fee2e2; color: #991b1b; }
+.form-group textarea, .pem-input { width: 100%; padding: 0.5rem; border: 1px solid #ccc; border-radius: 4px; font-family: monospace; font-size: 0.875rem; resize: vertical; }
+.form-group input[type="file"] { padding: 0.25rem 0; border: none; }
+.form-row { display: flex; gap: 1rem; }
+.form-row .form-group { flex: 1; }
+details { margin: 0.75rem 0; }
+details summary { cursor: pointer; color: #2563eb; font-weight: 600; margin-bottom: 0.5rem; }