feat(phase0): 工具链 + 契约快照测试，修复既有 bug

- 新增 pyproject.toml / pytest.ini / Makefile / requirements-dev.txt
- 新增 3 个契约快照测试（路由167/权限串148/表名25），守护前端与数据契约
- 修复 requirements.txt UTF-16 编码导致 pip 无法解析
- 修复 JobLog 未继承 Base 导致无法映射（fastapi_job_log 表缺失于 metadata）
- 修复 base_model.to_dict() 未序列化纯 date 类型（birthday 等导致 500）
- 补充 .gitignore（.env/缓存/上传目录）

Co-Authored-By: Claude <noreply@anthropic.com>

tests/contract/golden/tables.json

@@ -0,0 +1,27 @@
+[
+  "fastapi_ad",
+  "fastapi_ad_sort",
+  "fastapi_city",
+  "fastapi_config",
+  "fastapi_config_data",
+  "fastapi_dept",
+  "fastapi_dict",
+  "fastapi_dict_data",
+  "fastapi_item",
+  "fastapi_item_cate",
+  "fastapi_job",
+  "fastapi_job_log",
+  "fastapi_level",
+  "fastapi_link",
+  "fastapi_login_log",
+  "fastapi_member",
+  "fastapi_member_level",
+  "fastapi_menu",
+  "fastapi_notice",
+  "fastapi_operation_log",
+  "fastapi_position",
+  "fastapi_role",
+  "fastapi_role_menu",
+  "fastapi_user",
+  "fastapi_user_role"
+]