[FEATURE] Anchor user-scope hook commands to $HOME on POSIX targets so ~/.claude/settings.json stays portable across machines

Summary

User-scope installs (apm install -g) write hook command entries into ~/.claude/settings.json with the home directory expanded to a literal absolute path, e.g.

"command": "node \"/Users/alice/.claude/hooks/context-mode/hooks/pretooluse.mjs\""

~/.claude/settings.json is a file many people keep in a dotfiles repo shared across machines. A literal home prefix makes the tracked file differ per host (/Users/alice vs /home/alice), so every apm install -g on a second machine produces a diff of the same hooks with a different prefix.

The absolute rewrite itself is right (#1310 / #1354: hook commands resolve against the cwd, not the settings file), and #1394 correctly limited it to user scope. The ask is only about how user-scope paths are anchored on POSIX targets.

Proposal

For user-scope deploys on POSIX hosts, anchor the rewritten script path to $HOME instead of the expanded home directory:

"command": "node \"$HOME/.claude/hooks/context-mode/hooks/pretooluse.mjs\""

Claude Code and Codex run hook commands through a shell, so $HOME expands at invocation time regardless of cwd, which keeps the #1310 fix intact while making the merged file host-independent. Windows targets would keep the current absolute form (%USERPROFILE% semantics differ and #2408 shows cwd handling is already special there).

The same applies to the apm-hooks.json ledger, so adoption on the next install matches the $HOME form.

Evidence

Tested on apm 0.29.0 (656f3d6) with a scratch HOME:

• Rewriting the merged settings.json entries to $HOME/... by hand and reinstalling re-adds the absolute entries next to them (14 → 28 hooks).
• Rewriting both settings.json and apm-hooks.json to $HOME/... and reinstalling: apm adopts them (no duplicates) but rewrites them back to absolute. apm uninstall -g <pkg> still removes the right entries in that state.

So the change is contained in _rewrite_command_for_target / _deploy_root_for_hook_rewrite in src/apm_cli/integration/hook_integrator.py: when user_scope is set and the target is a POSIX shell-executed hook, emit "$HOME/" + relative_to(home) instead of (deploy_root / target_rel).resolve().

Environment

• apm 0.29.0 from commit 656f3d6e6dbade369b6fc8727a4eb7b164409b6d
• macOS 15 (arm64) and Linux x86_64, targets claude and codex, user scope

Start in src/apm_cli/integration/hook_integrator.py, reading _rewrite_command_for_target and _deploy_root_for_hook_rewrite. Trace user-scope POSIX and Windows handling, then verify that both settings.json and the apm-hooks.json ledger use the portable $HOME form on POSIX while Windows retains its existing absolute behavior.