Introduce OpenAPI specs (#4351)

* wip

* wip

* wip

* Update index.ts

* Update gen-openapi-spec.ts

* Update api.ja-JP.md

* Fix

* Improve doc

* Update gen-openapi-spec.ts

* Update redoc.html

* Improve doc

* Update gen-openapi-spec.ts

* Improve doc

* Update CHANGELOG.md

src/server/api/call.ts

@@ -21,6 +21,7 @@ export default async (endpoint: string, user: IUser, app: IApp, data: any, file?
 			message: 'No such endpoint.',
 			code: 'NO_SUCH_ENDPOINT',
 			id: 'f8080b67-5f9c-4eb7-8c18-7f1eeae8f709',
+			httpStatusCode: 404
 		});
 	}
 
@@ -33,6 +34,7 @@ export default async (endpoint: string, user: IUser, app: IApp, data: any, file?
 			message: 'Credential required.',
 			code: 'CREDENTIAL_REQUIRED',
 			id: '1384574d-a912-4b81-8601-c7b1c4085df1',
+			httpStatusCode: 401
 		});
 	}
 
@@ -63,6 +65,7 @@ export default async (endpoint: string, user: IUser, app: IApp, data: any, file?
 				message: 'Rate limit exceeded. Please try again later.',
 				code: 'RATE_LIMIT_EXCEEDED',
 				id: 'd5826d14-3982-4d2e-8011-b9e9f02499ef',
+				httpStatusCode: 429
 			});
 		});
 	}