Feature Request: Dynamic reloading of slash commands

Current Behavior

Slash commands (.claude/commands/*.md) are loaded and cached when Claude Code starts.
If you modify an existing command file, you must restart Claude Code to see the changes.

Expected Behavior

Slash command files should be read dynamically on each invocation, allowing developers
to edit and test commands without restarting the CLI.

Why This Matters

1. Developer Experience: Iterating on custom commands requires constant restarts
2. Fast Prototyping: Testing prompt changes should be instant
3. Industry Standard: Most tools (web servers, template engines) reload configs on-the-fly
4. Performance: Reading a small markdown file is negligible (~1ms)

Steps to Reproduce Current Behavior

1. Create a slash command: .claude/commands/test.md
2. Start Claude Code
3. Modify the command file (add text/change prompt)
4. Run /test → old version still executes
5. Must restart Claude Code to see changes

Proposed Solution

Read command files on each invocation instead of caching at startup.
Only the command list (for autocomplete) needs to be cached.

Workaround

Currently: restart Claude Code after every change to command files.