feat: Add npm install / npm ls command support

Currently rtk npm only intercepts npm run commands. npm install and npm ls are not rewritten by the hook engine (rtk hook claude / rtk rewrite).

npm install output can be very verbose — dependency trees, audit warnings, deprecation notices — often 200+ lines. This is a significant token waste when used in LLM CLI contexts.

Observed behavior:

$ rtk hook check "npm run build"    # → rtk npm run build ✓
$ rtk hook check "npm install"      # → exit 1, no rewrite ✗
$ rtk hook check "npm ls"           # → exit 1, no rewrite ✗

Expected: npm install → rtk npm install with compact output (strip progress bars, dependency tree noise, keep errors/warnings/audit summary).

Usage context: Monorepo with 12+ services, npm install called ~104 times/month across Claude Code sessions. Estimated ~15-20K tokens saveable.