feat(core): shared domain error classes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/core/src/errors.ts

@@ -0,0 +1,42 @@
+/** Authentication or authorisation failure; `code` names the reason (e.g. "invalid_credentials"). */
+export class AuthError extends Error {
+  override readonly name = "AuthError";
+  constructor(readonly code: string) {
+    super(code);
+  }
+}
+
+/** Input rejected by validation. */
+export class ValidationError extends Error {
+  override readonly name = "ValidationError";
+  readonly code = "validation";
+  constructor(
+    readonly field: string,
+    readonly reason: string,
+  ) {
+    super(`${field}: ${reason}`);
+  }
+}
+
+/** Encryption or decryption failure (e.g. wrong key, tampered ciphertext). */
+export class CryptoError extends Error {
+  override readonly name = "CryptoError";
+  readonly code = "crypto";
+}
+
+/** Import or restore failure; `code` names the reason. */
+export class ImportError extends Error {
+  override readonly name = "ImportError";
+  constructor(readonly code: string) {
+    super(code);
+  }
+}
+
+/** A requested record does not exist (or is not visible to the caller). */
+export class NotFoundError extends Error {
+  override readonly name = "NotFoundError";
+  readonly code = "not_found";
+  constructor(readonly what: string) {
+    super(`${what} not found`);
+  }
+}