Refactor authorization models to remove circular imports and update gitignore

- Updated .gitignore with standard Python project exclusions and removed redundant entries
- Modified PermissionModel to remove direct imports and use string references for relationships
- Modified AuthorizationResourceModel to remove direct imports and use string references for relationships
- Modified RolePermissionModel to remove direct imports and use string references for relationships
- Modified UserHasRoleModel to remove direct imports and use string references for relationships

This change eliminates circular import dependencies between authorization models while maintaining all existing functionality and relationships. The gitignore file now follows standard conventions for Python projects.

Author: qwen-intl

.gitignore

@@ -1,50 +1,33 @@
-```
+```gitignore
+# Python cache
 __pycache__/
 *.pyc
 *.pyo
 *.pyd
-*.log
-*.tmp
-*.swp
-.DS_Store
-Thumbs.db
+
+# Dependencies
+.venv/
+venv/
+env/
 .env
 .env.local
 .env.*
+
+# Logs
+*.log
+
+# Coverage
+.coverage
+htmlcov/
+coverage/
+
+# IDE
 .vscode/
 .idea/
-node_modules/
-venv/
-.venv/
-dist/
-build/
-target/
-.gradle/
-.mypy_cache/
-.pytest_cache/
-coverage/
-htmlcov/
-.coverage
-*.zip
-*.gz
-*.tar
-*.tgz
-*.bz2
-*.xz
-*.7z
-*.rar
-*.zst
-*.lz4
-*.lzh
-*.cab
-*.arj
-*.rpm
-*.deb
-*.Z
-*.lz
-*.lzo
-*.tar.gz
-*.tar.bz2
-*.tar.xz
-*.tar.zst
+*.swp
+*.swo
+
+# OS
+.DS_Store
+Thumbs.db
 ```