Feature request: customisable command palette showing built-in, skill, and user-defined commands

Currently Claude Code has built-in slash commands (\/help\, \/clear\, etc.), skill commands (\/security-review\, \/ultrareview\, etc.), and user-definable keywords via \CLAUDE.md\. These three tiers exist but there's no unified way to discover or display them.

Proposed feature: A first-class command palette (e.g. triggered by \/commands\ or a keyboard shortcut) that renders all available commands in a single view, with a Type column distinguishing Built-in / Skill / Custom. Custom commands would be defined in \CLAUDE.md\ and picked up automatically.

This would make Claude Code significantly more approachable for new users (discoverability) while giving power users a clean way to document and surface their own workflow shortcuts. The \CLAUDE.md\-based customisation already works well — this just gives it a proper UI.