feat: add project-owned error catalogs and HTTP 200 failure contracts

examples/contracts/errors.api

@@ -0,0 +1,36 @@
+syntax = "v1"
+
+errorCatalog CommonErrors (
+    defaultStatus: 200
+    errors: {
+        "UsernameInvalid": {"key": "USERNAME_INVALID", "code": 400002, "message": "用户名格式不正确"},
+        "PasswordInvalid": {"key": "PASSWORD_INVALID", "code": 400002, "message": "密码格式不正确"},
+        "PermissionDenied": {"key": "PERMISSION_DENIED", "status": 403, "code": 403001, "message": "没有权限"}
+    }
+)
+
+response CommonResponse (
+    codeType: int32
+    successCode: 0
+    errorCode: 9999
+    body: {"ok": "${ok}", "code": "${code}", "data": "${data}"}
+    errorBody: {"ok": "${ok}", "code": "${code}", "msg": "${message}"}
+)
+
+type TokenResponse {
+    Token string `json:"token"`
+}
+
+@server (
+    group: account
+    response: CommonResponse
+    errors: UsernameInvalid, PasswordInvalid, PermissionDenied
+)
+service errors-api {
+    @handler token
+    post /token returns (TokenResponse)
+
+    @response raw
+    @handler raw
+    get /raw returns (TokenResponse)
+}