Docs: clarify whether /compact reloads user-level ~/.claude/CLAUDE.md, not just project-root CLAUDE.md

Title: Docs: clarify whether `/compact` reloads user-level `~/.claude/CLAUDE.md`, not just project-root CLAUDE.md

## Summary

The troubleshooting/docs content around `/compact` explicitly states that
**project-root** `CLAUDE.md` is re-read after compaction. It does not say
anything about the **user-level** `~/.claude/CLAUDE.md` — even though that
file is documented elsewhere as its own distinct scope, loaded alongside the
project-root file at session start via the same mechanism.

This leaves it unclear whether:

- `/compact` also re-reads `~/.claude/CLAUDE.md` from disk (picking up
mid-session edits), or
- only project-root `CLAUDE.md` gets this treatment, and `~/.claude/CLAUDE.md`
is fixed to whatever was loaded at session start until a restart.

## Why this should be documented

It's architecturally plausible both files are reloaded the same way, since
they're loaded through the same mechanism at session start — but that's an
assumption, not something the docs currently confirm. Anyone who wants to
rely on `~/.claude/CLAUDE.md` for standing instructions and needs to know
whether an edit takes effect after `/compact` (vs. requiring a session
restart) currently has to test it themselves rather than find it documented.

## Suggested addition

A one-line clarification next to the existing "`/compact` re-reads
project-root CLAUDE.md" note, stating explicitly whether user-level
`~/.claude/CLAUDE.md` is included in that reload or not.

## Environment

- Claude Code CLI, VS Code extension context

Start with the troubleshooting/docs content that describes `/compact` and the existing note about re-reading project-root `CLAUDE.md`. Verify whether user-level `~/.claude/CLAUDE.md` is also reloaded, then add a one-line clarification stating the documented behavior.

索引モデルが issue の本文から書いたものです。