/jfrog-init — verify and guide JFrog plugin readiness

First output must be a tool call, not text. No "I'll start..." preamble.

Walks a fixed, ordered checklist and stops at the first non-passing result, guiding the user through the matching fix before re-checking. Every detector in scripts/ is idempotent, read-only, JSON-emitting, and implemented in Node (.mjs), so the same detector runs unmodified on macOS, Linux, and Windows. Step 3's web-login uses this skill's own local .mjs scripts, same as every other step. The one interactive fix step that isn't a Node script at all is Step 1's Node install itself — a missing Node can't run a .mjs installer, so that one step branches on OS or shell directly.