fix(update-skills): prefer --scope managed for IT installs (0.27.1)

[richheadley]

Problem

The /update-skills coach (and the onboarding cheat sheet) led with:

claude plugin update mothy@mothy-marketplace

At Moth+Flame, installs are almost always Scope: managed (IT push). That bare update then fails with Plugin "mothy" is not installed at scope user, wasting a coaching round trip before the coach fell back to --scope managed in an "if error" subsection.

Fix

1. plugins/mothy/skills/update-skills/SKILL.md

   • Step 1 branches on the Scope column from claude plugin list (managed vs user/project/local).
   • Step 2 itself leads with claude plugin update mothy@mothy-marketplace --scope managed when Scope was managed (still after marketplace update). Bare update is only for hand installs.
   • Wrong-scope errors remain as a fallback, not the primary path.

2. docs/onboarding-claude-code-skills.md — same: managed is the normal M+F path; bare update only for hand installs.

3. plugins/mothy/docs/ONBOARDING.md — no change; it only documents first-time marketplace add + install, not the update sequence.

4. Version — patch bump 0.27.0 → 0.27.1 in plugin.json + marketplace.json.

Step 2 managed-first update path

Follow-up (not in this repo)

The skill still points Chat/Cowork at the parallel playbook mothy-mcp/playbooks/update-skills.md (update_skills_playbook_get). That file is not in mothy-plugins; mothy-mcp may need a matching edit so the MCP coach does not keep leading with the bare user-scope update.

Test plan

• node --test tests/ (Node 20, same as CI / pre-push)
• Assert Step 2 lists --scope managed before the bare update command
• Manual: with a managed install, coach from Step 1 list output should issue --scope managed without an intervening bare-update failure

_{To show artifacts inline, enable in settings.}