Same root cause as #587/#591 — Claude Code's runtime loader rejects
array-form skills paths like ["./content-production", "./ai-seo", ...]
even when each entry is a valid subdirectory containing SKILL.md.
`claude plugin validate` accepts them but the loader does not.
The proven canonical layout (used by self-improving-agent in #536):
<plugin>/
├── .claude-plugin/plugin.json skills: "./skills"
└── skills/
├── <skill-1>/SKILL.md
├── <skill-2>/SKILL.md
└── ...
Restructured 9 multi-skill domain plugins:
- business-growth (4 skills moved)
- c-level-advisor (28)
- engineering (36)
- engineering-team (32)
- finance (2)
- marketing-skill (43)
- product-team (12)
- project-management (8)
- ra-qm-team (13)
Also fixed standalone plugins that had root SKILL.md + ./skills/ subdir
(agenthub, autoresearch-agent, executive-mentor, playwright-pro). The
loader rejected them despite skills="./skills" because of the conflicting
root SKILL.md (compare self-improving-agent which works because PR #536
moved its root SKILL.md). Moved each root SKILL.md into ./skills/<name>/.
Restored standalone plugin folders to their original paths after the
multi-skill restructure swept them into parent skills/ directories
(marketplace.json source paths require original locations).
Removed 7 orphaned marketplace entries that pointed to skill folders
without their own plugin.json (content-creator, demand-gen,
fullstack-engineer, aws-architect, product-manager, scrum-master,
skill-security-auditor) — these were already non-functional.
Bumped patch versions on every changed plugin and synced
marketplace.json. Marketplace now lists 29 working plugins (down
from 36).
After merge: users run `/plugin marketplace update claude-code-skills`
followed by `/plugin update --all` to pick up the working layout.
