chore: enhance project metadata, tooling, and documentation

**Project Configuration:**
- Enhance pyproject.toml with comprehensive metadata, keywords, and classifiers
- Add LICENSE file (MIT) for proper open-source distribution
- Add PUBLISHING.md with comprehensive publishing guidelines
- Update .gitignore to exclude tool artifacts (.cache, .pytest_cache, .ruff_cache, .ty_cache)
- Ignore documentation working directories (.docs, .full-review, docs/plans, docs/sessions)

**Documentation:**
- Add extensive Unraid API research documentation
  - API source code analysis and resolver mapping
  - Competitive analysis and feature gap assessment
  - Release notes analysis (7.0.0, 7.1.0, 7.2.0)
  - Connect platform overview and remote access documentation
- Document known API patterns, limitations, and edge cases

**Testing & Code Quality:**
- Expand test coverage across all tool modules
- Add destructive action confirmation tests
- Improve test assertions and error case validation
- Refine type annotations for better static analysis

**Tool Improvements:**
- Enhance error handling consistency across all tools
- Improve type safety with explicit type annotations
- Refine GraphQL query construction patterns
- Better handling of optional parameters and edge cases

This commit prepares the project for v0.2.0 release with improved
metadata, comprehensive documentation, and enhanced code quality.

Co-authored-by: Claude <noreply@anthropic.com>

tests/test_health.py

@@ -108,6 +108,16 @@ class TestHealthActions:
             with pytest.raises(ToolError, match="broken"):
                 await tool_fn(action="diagnose")
 
+    async def test_diagnose_success(self, _mock_graphql: AsyncMock) -> None:
+        """Diagnose returns subscription status when modules are available."""
+        tool_fn = _make_tool()
+        mock_status = {
+            "cpu_sub": {"runtime": {"connection_state": "connected", "last_error": None}},
+        }
+        with patch("unraid_mcp.tools.health._diagnose_subscriptions", return_value=mock_status):
+            result = await tool_fn(action="diagnose")
+        assert "cpu_sub" in result
+
     async def test_diagnose_import_error_internal(self) -> None:
         """_diagnose_subscriptions catches ImportError and returns error dict."""
         import builtins