chore: remove helm chart (migrated to cbcoutinho/helm-charts)

The helm chart has been migrated to a dedicated repository at
https://github.com/cbcoutinho/helm-charts. This removes the chart
source, release workflow, bump script, and updates all documentation
to point to the new repository.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

scripts/bump-mcp.sh

@@ -65,7 +65,7 @@ fi
 echo "$output"
 echo ""
 echo "✓ MCP server version bumped successfully"
-echo "  Updated: pyproject.toml, Chart.yaml:appVersion"
+echo "  Updated: pyproject.toml"
 echo "  Tag format: v\${version}"
 echo ""
 echo "Next steps:"