Onboarding skill for DS4: a docs-grounded agent skill tutor

[maeste]

Proposal

An agent skill that onboards newcomers to DS4 as a guided tutor, grounding
every answer in the repository's own sources.

What it does

• Teaches DS4 step by step (what it is → prerequisites → model download →
  build → first run → server/agent/bench/eval → cross-cutting concepts →
  debugging) following the project's own incremental --help philosophy.
• Answers only from the certified corpus: README.md, MODEL_CARD.md,
  the */README.md files, and the real CLI --help output (source of record
  ds4_help.c / ds4_help.h). No web, no training-data guesses.
• Every project claim is cited with a clickable file:line plus a GitHub
  permalink to the same line.
• Replies in the user's language, keeping commands/flags/paths verbatim.
• Never runs work commands for the user (no generate/serve/download/build/
  bench/eval) — it hands over the exact command to copy. The only execution it
  performs is --help.

Why upstream

It keeps newcomers anchored to the real docs and CLI help, and the citation
rule doubles as a lightweight doc-consistency check.

Open questions

• Preferred location: .agents/skills/ with .claude as a symlink (current),
  or another convention?
• Should it live in-repo or in a separate companion repo?

A PR implementing this is linked below.