docs(hooks): clarify plugin auto-installs hooks; update manual install to use CLI

[ichoosetoaccept]

What does this PR do?

The hooks guide told all users to manually add hooks to settings.json using absolute bash script paths. This is wrong in two ways:

1. Plugin users don't need to do anything — hooks are registered automatically by the Claude Code plugin runtime (loaded in-memory from hooks/hooks.json at session start). Adding manual entries on top causes both Stop and PreCompact hooks to fire twice per event.

2. Non-plugin users (pip/uv standalone installs) should use mempalace hook run CLI, not absolute paths to internal bash wrapper scripts.

Changes:

• Add Via Plugin (Recommended) section — hooks are automatic, with a double-registration warning
• Rename old section to Without Plugin (Manual) and update commands to mempalace hook run --hook stop --harness claude-code
• Update Codex section to use mempalace hook run --hook stop --harness codex
• Remove matcher from Stop/PreCompact examples (matchers are for tool-name filtering in PreToolUse/PostToolUse, not event-based hooks)
• Remove instruction to edit bash scripts directly from Configuration section

Related to #408 — the old manual workaround existed partly because earlier versions used python3 -m mempalace which silently failed on uv installs. With 3.3.3 using mempalace hook run, plugin-managed hooks work correctly.

How to test

Install via Claude Code plugin marketplace, run /hooks — both Stop and PreCompact appear automatically, sourced from ~/.claude/plugins/*/hooks/hooks.json. Nothing in settings.json. Check ~/.mempalace/hook_state/hook.log to confirm saves fire.

Checklist

• Tests pass (python -m pytest tests/ -v)
• No hardcoded paths
• Linter passes (ruff check .)

[milla-jovovich]

Thanks for catching the double-firing — clean fix.✨