refactor: make gitea a self-contained Cline skill

Relocate the script into the skill (skills/gitea/scripts/gitea_mcp.py) and add a
PEP 723 dependency block, so `uv run scripts/gitea_mcp.py` provisions deps with no
install step and the skill folder is portable (drop into ~/.cline/skills/). Drop
the non-standard `metadata` frontmatter — Cline only recognizes name + description.

- .mcp.json points at the relocated script and runs with --no-project (PEP 723)
- SKILL.md uses relative scripts/ paths; metadata block removed
- find_config walks up the tree to locate config.json (skill root or plugin root)
- tests import gitea_mcp via pytest pythonpath; README/CLAUDE paths updated

Tests: 119 passed, 92% coverage. Standalone list-tools verified via uv --no-project.

tests/smoke/test_registration.py

@@ -1,5 +1,5 @@
 import asyncio
-from server.gitea_mcp import mcp
+from gitea_mcp import mcp
 
 EXPECTED_TOOL_COUNT = 66