feat(endpoint): 端点默认 body_rules 机制与 Codex 规则回填

- EndpointDefinition 新增 default_body_rules 字段，openai:cli/compact 配置 Codex 默认规则
- 创建端点时若未指定 body_rules 则自动填充对应格式的默认值
- 新增 GET /defaults/{api_format}/body-rules 接口查询默认规则
- 前端 EndpointFormDialog 增加"重置请求体"按钮，支持一键恢复默认
- Alembic 迁移回填已有 Codex 端点的默认 body_rules
- 新增 metadata 和 endpoint 创建默认值的单元测试

tests/unit/test_api_format_metadata.py

@@ -0,0 +1,61 @@
+import pytest
+
+import src.core.api_format.metadata as metadata
+from src.core.api_format.enums import ApiFamily, EndpointKind
+from src.core.api_format.metadata import EndpointDefinition, get_default_body_rules_for_endpoint
+
+
+def test_get_default_body_rules_for_endpoint_returns_empty_for_invalid() -> None:
+    assert get_default_body_rules_for_endpoint("not-a-valid-signature") == []
+
+
+def test_get_default_body_rules_for_endpoint_returns_empty_for_no_rules() -> None:
+    """claude:chat 没有配置 default_body_rules，应返回空列表。"""
+    assert get_default_body_rules_for_endpoint("claude:chat") == []
+
+
+def test_get_default_body_rules_for_endpoint_returns_codex_rules() -> None:
+    """openai:cli 和 openai:compact 应返回 Codex 默认规则。"""
+    cli_rules = get_default_body_rules_for_endpoint("openai:cli")
+    assert len(cli_rules) == 5
+    actions = [r["action"] for r in cli_rules]
+    assert actions == ["drop", "drop", "drop", "set", "set"]
+    assert cli_rules[0]["path"] == "max_output_tokens"
+    assert cli_rules[1]["path"] == "temperature"
+    assert cli_rules[2]["path"] == "top_p"
+    assert cli_rules[3] == {"action": "set", "path": "store", "value": False}
+    assert cli_rules[4]["path"] == "instructions"
+    assert cli_rules[4]["condition"]["op"] == "not_exists"
+
+    compact_rules = get_default_body_rules_for_endpoint("openai:compact")
+    assert compact_rules == cli_rules
+
+
+def test_get_default_body_rules_for_endpoint_returns_deep_copy(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    definition = EndpointDefinition(
+        api_family=ApiFamily.OPENAI,
+        endpoint_kind=EndpointKind.CLI,
+        default_body_rules=(
+            {
+                "action": "set",
+                "path": "metadata",
+                "value": {"source": "default"},
+            },
+        ),
+    )
+
+    monkeypatch.setattr(metadata, "resolve_endpoint_definition", lambda _value: definition)
+
+    rules = get_default_body_rules_for_endpoint("openai:cli")
+    assert rules == [
+        {
+            "action": "set",
+            "path": "metadata",
+            "value": {"source": "default"},
+        }
+    ]
+
+    rules[0]["value"]["source"] = "changed"
+    assert definition.default_body_rules[0]["value"]["source"] == "default"