What would you like to be added?

Add a list subcommand to the existing /commands command.

When executed (/commands list), it should fetch and display the list of loaded .toml files from the directories that are evaluated by the reload command (e.g., user-level ~/.gemini/commands/, project-level <project>/.gemini/commands/, MCP prompts, and extensions).

Why is this needed?

Currently, the /commands command only provides a reload subcommand. There is no convenient way for users to verify which custom commands or prompt files are currently recognized by the CLI without manually navigating the file system.

Adding a list subcommand significantly improves visibility and the overall developer experience by allowing users to quickly verify their loaded commands directly within the CLI.

Additional context

I have already implemented this feature locally, including unit tests, and verified that it passes npm run preflight.
I will assign this issue to myself and open a PR shortly.