#207 feat(skills): add BetterWright/betterwright agent skills

Summary

Adds BetterWright/betterwright to the external skills pipeline for SHUN-3592.

• Declares all six skills in SKILLS.txt (alpha order after better-auth/skills): 1password, bitwarden, browser, credential-manager, full-stack-e2e-review, github
• Locks them in skills-lock.json (573 → 579)
• Passes --full-depth to skills add in make skills-install / bootstrap warn so nested skills install when a root SKILL.md is present (without it, only browser is discovered)

Test plan

• make skills-lock includes all six BetterWright entries with skillPath + skillFolderHash
• make skills-install reports all skills installed when present (idempotent)
• After removing the six dirs under ~/.agents/skills, make skills-install reinstalls all six (including nested) via --full-depth
• Reviewer: make skills-install on a clean machine pulls BetterWright skills without copying into skills/

  

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Summary by cubic

Adds the six BetterWright/betterwright skills to the external skills pipeline and fixes nested skill installation when a root SKILL.md is present.

• Declares 1password, bitwarden, browser, credential-manager, full-stack-e2e-review, and github in SKILLS.txt and locks them in skills-lock.json.
• Passes --full-depth to skills add in make skills-install and bootstrap warnings so nested skills install alongside the root browser skill; previously only browser was discovered.