feat: scaffold gitea-mcp package with module rename

- Copied source from leo-claude-mktplace/mcp-servers/gitea/ v1.0.0
- Renamed module: mcp_server → gitea_mcp (all imports updated)
- Created pyproject.toml for standalone package identity
- Preserved all existing tools and test suite
- MCP SDK imports unchanged

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

requirements.txt

@@ -0,0 +1,4 @@
+mcp>=0.9.0
+python-dotenv>=1.0.0
+requests>=2.31.0
+pydantic>=2.5.0