`codegraph node` was defined with a required `<name>` positional, so
commander.js rejected `codegraph node -f <file>` with "missing required
argument 'name'" before the action ran — making file-read mode (the CLI
face of the codegraph_node MCP tool's file mode) unreachable. The action
body already handled an absent name.
Make `name` optional (`[name]`), validate that a symbol or a file is
supplied (friendly usage hint instead of a cryptic commander error when
neither is), and guard the name-based arg branches so they never run on
undefined. Adds an end-to-end regression test across all four paths.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
