```

refactor: 移除审批和回写功能模块

移除了整个审批(approvals)和官方回写(writebacks)功能模块，
包括相关模型、路由、服务和配置项。更新了数据库迁移文件，
删除了相关的审批请求表和官方回写运行表。同时从API路由器中
移除了相应的路由，并调整了安全常量和字段验证器以匹配变更。
```

app/core/config.py

@@ -21,6 +21,7 @@ class Settings(BaseSettings):
     app_name: str = "Company AI Management Platform"
     app_env: str = "local"
     debug: bool = False
+    read_only_mode: bool = True
     api_prefix: str = "/api/v1"
     api_key: str | None = None
     api_actor: str = ActorValue.API
@@ -28,9 +29,6 @@ class Settings(BaseSettings):
     audit_api_key: str | None = None
     audit_api_actor: str = ActorValue.AUDITOR
     audit_api_keys: list[dict[str, Any]] = Field(default_factory=list)
-    approval_api_key: str | None = None
-    approval_api_actor: str = ActorValue.APPROVER
-    approval_api_keys: list[dict[str, Any]] = Field(default_factory=list)
     cors_origins: list[str] = Field(default_factory=lambda: ["*"])
     mask_sensitive_responses: bool = True
     masked_response_fields: list[str] = Field(default_factory=list)
@@ -50,8 +48,6 @@ class Settings(BaseSettings):
     feishu_verification_token: str | None = None
     feishu_encrypt_key: str | None = None
     feishu_default_chat_id: str | None = None
-    feishu_approval_approver_ids: Annotated[list[str], NoDecode] = Field(default_factory=list)
-
     model_provider: str = DEFAULT_MODEL_PROVIDER
     openclaw_base_url: str = "http://127.0.0.1:2070"
     openclaw_http_url: str | None = None
@@ -84,11 +80,6 @@ class Settings(BaseSettings):
     legacy_project_sync_cron_minute: int = 0
     legacy_task_sync_cron_hour: int = 2
     legacy_task_sync_cron_minute: int = 30
-    official_writeback_enabled: bool = False
-    official_api_base_url: str | None = None
-    official_api_token: str | None = None
-    official_api_timeout_seconds: float = 10.0
-
     @field_validator("cors_origins", mode="before")
     @classmethod
     def parse_cors_origins(cls, value: Any) -> list[str]:
@@ -107,7 +98,6 @@ class Settings(BaseSettings):
     @field_validator(
         "openclaw_allowed_tools",
         "openclaw_allowed_actions",
-        "feishu_approval_approver_ids",
         mode="before",
     )
     @classmethod
@@ -143,7 +133,7 @@ class Settings(BaseSettings):
             return [str(item).strip() for item in data if str(item).strip()]
         return [item.strip() for item in text.split(",") if item.strip()]
 
-    @field_validator("api_keys", "audit_api_keys", "approval_api_keys", mode="before")
+    @field_validator("api_keys", "audit_api_keys", mode="before")
     @classmethod
     def parse_service_keys(cls, value: Any) -> list[dict[str, Any]]:
         if value is None or value == "":