feat(auth): extend User entity with authentication fields

- Add username field
- Add password_hash for bcrypt hash storage
- Add email_verified and email_verification_token for email verification
- Add password_reset_token and password_reset_expires_at for password reset
- Add last_login_at and last_login_ip for login tracking
- Backward compatible with existing code (all new fields have defaults)

Phase 4 Task 5/68 completed

packages/domain/entities.py

@@ -24,6 +24,15 @@ class User:
     id: str
     email: str
     display_name: str
+    username: str = ""
+    # 认证相关字段
+    password_hash: str = ""
+    email_verified: bool = False
+    email_verification_token: str | None = None
+    password_reset_token: str | None = None
+    password_reset_expires_at: datetime | None = None
+    last_login_at: datetime | None = None
+    last_login_ip: str | None = None
     created_at: datetime = field(default_factory=lambda: datetime.now(timezone.utc))