hook: settings surface locates project via ${PWD:-.}, launcher via CLAUDE_PROJECT_DIR (P3)

[systemfsoftware-maker]

Source: ce-code-review run 20260830-212446-4b8b0529 (adversarial P3/75 + correctness P3).

What

.claude/settings.json uses ${PWD:-.} for direnv exec and the flake.nix probe; hooks/run.ts uses CLAUDE_PROJECT_DIR. Claude started from a nested package dir of a flake monorepo takes the pnpm-install guidance branch on the settings surface while the plugin reports correctly.

Fix

direnv exec \"${CLAUDE_PROJECT_DIR:-${PWD:-.}}\" comment-checker and [ -f \"${CLAUDE_PROJECT_DIR:-${PWD:-.}}\"/flake.nix ] so both surfaces agree on project root.

Carried by PR #92: #92