fix(admin): 优先级脏检查、base_url 校验、usage detail 延迟加载及导入数据验证

- 前端优先级管理: 保存时对比原始快照，仅提交实际变更的 provider/key 优先级，
  并限制并发请求数(SAVE_CONCURRENCY=6)，避免无效 API 调用
- handler_adapter_base: _normalize_test_base_url 改为 _validate_test_base_url，
  移除对 dict 类型 base_url 的兼容，严格要求字符串输入
- provider_query: 新增 _require_test_endpoint_base_url，在测试链路提前校验
  endpoint.base_url 类型和非空
- system.py: 导入 endpoint 时通过 ProviderEndpointCreate 模型校验数据，
  拒绝非法 base_url 类型(如 dict)
- usage detail: 使用 defer() 延迟加载 body 列，通过 SQL CASE 表达式在
  数据库端计算 has_*_body 标记，减少不必要的大字段传输
- provider routes: 新建 provider 时 priority=0 边界处理，clamp 并 shift

tests/unit/test_admin_system_key_formats.py

@@ -1,4 +1,7 @@
+import pytest
+
 from src.api.admin.system import AdminExportConfigAdapter, AdminImportConfigAdapter
+from src.core.exceptions import InvalidRequestException
 from src.services.provider_ops.types import SENSITIVE_CREDENTIAL_FIELDS
 
 
@@ -114,3 +117,27 @@ def test_import_provider_config_encrypts_refresh_token() -> None:
     assert result["provider_ops"]["connector"]["credentials"]["refresh_token"] == "enc:rt-1"
     assert result["provider_ops"]["connector"]["credentials"]["api_key"] == "enc:key-1"
     assert config["provider_ops"]["connector"]["credentials"]["refresh_token"] == "rt-1"
+
+
+def test_import_endpoint_payload_rejects_dict_base_url() -> None:
+    with pytest.raises(InvalidRequestException, match="导入 Endpoint 失败"):
+        AdminImportConfigAdapter._normalize_import_endpoint_payload(
+            "provider-1",
+            {
+                "api_format": "claude:chat",
+                "base_url": {"url": "https://api.anthropic.com"},
+            },
+        )
+
+
+def test_import_endpoint_payload_normalizes_base_url() -> None:
+    result = AdminImportConfigAdapter._normalize_import_endpoint_payload(
+        "provider-1",
+        {
+            "api_format": "claude:chat",
+            "base_url": "https://api.anthropic.com/",
+        },
+    )
+
+    assert result["base_url"] == "https://api.anthropic.com"
+    assert result["api_format"] == "claude:chat"