docs: describe shipping CLI utilities in a skill per supported language

[ivanopcode]

What

New docs/authoring-cli-commands.md (Russian, board task TASK-260827-1r6mer): the author-facing guide for shipping CLI utilities with a skill.

• The two placements: embedded build_roots inside the package versus an external build repository, and when each fits.
• The go-v1 admission matrix derived from src/csk validation code (vendored deps with -mod=vendor, no network, toolchain identity, the rejections, macOS/Windows-only platform gate with per-driver refusal points).
• Schema-8 modules: the containment rule stated the way _reject_overlaps actually enforces it, with build_module_root_containment_invalid.
• Script commands and the script_execution_policy_unsupported refusal of script-worker-v1.
• One worked example per supported path, each validated with live csk skill check output.
• An honest planned-languages paragraph (kotlin/swift/rust are not shipped; the actual validation error is named), plus the cross-manager note that Curator's adapter workstream widens its own set independently.

Linked from the README, docs/cli.md, and docs/skill-authoring.md.

Review evidence

Two review cycles (claude-opus-5): cycle 1 caught a fabricated error literal and an inverted containment rule; cycle 2 re-derived every identifier against src/csk and re-ran the examples from fixtures, verdict ACCEPTED.