feat: add v1 management APIs, audit logs, and import/export

src/models/audit.ts

@@ -0,0 +1,10 @@
+export interface AuditLogEntry {
+  id: string;
+  ts: string;
+  actorId: string;
+  action: string;
+  target?: string;
+  status: 'ok' | 'error';
+  message?: string;
+  meta?: Record<string, unknown>;
+}

src/models/errors.ts

@@ -0,0 +1,19 @@
+export type ErrorCode =
+  | 'PERMISSION_DENIED'
+  | 'NOT_FOUND'
+  | 'ALREADY_EXISTS'
+  | 'VALIDATION_ERROR'
+  | 'FIELD_NOT_QUERYABLE'
+  | 'INVALID_SUPERVISOR'
+  | 'REGISTRAR_DENIED';
+
+export class YonexusError extends Error {
+  constructor(
+    public readonly code: ErrorCode,
+    message: string,
+    public readonly details?: Record<string, unknown>
+  ) {
+    super(message);
+    this.name = 'YonexusError';
+  }
+}