Remove duplicate Claude marketplace skills

[omriariav]

Summary

• Remove the duplicate skills component declaration from the Claude marketplace gws entry.
• Keep .claude-plugin/plugin.json as the single canonical owner of the skills and hooks components.
• Add focused regression coverage that rejects marketplace component duplication while verifying canonical plugin.json ownership.

Rationale

Claude Code marketplace installation can encounter a runtime component conflict when the marketplace entry repeats components already declared by the plugin manifest. The marketplace now identifies the plugin only; component contents are unchanged.

Validation

• claude plugin validate .claude-plugin/marketplace.json
• claude plugin validate --strict .claude-plugin/marketplace.json
• go test ./cmd -run '^(TestMarketplaceJSON_Valid|TestPluginHookManifestsUseOneEntrypointPerEvent)$' -count=1
• git diff --check
• PATH-pinned make ci (0 lint issues)

Validator limitation

The standalone Claude validator passes both before and after this change, so it does not reproduce the marketplace-install runtime conflict. The focused regression test protects the manifest ownership rule directly.

[github-actions]

Summary

Removes duplicate Claude plugin skill declarations from marketplace.json and updates tests to verify plugin.json owns skills and hooks.

What looks good

• Canonical component paths are validated.
• Duplicate marketplace components are explicitly rejected.
• JSON remains valid and git diff --check passes.
• Existing tests separately verify all expected skill directories.
• No command documentation updates are needed.

Issues found

None. The PR is clean and ready to merge.

Test execution was blocked by the read-only environment preventing Go cache creation; this was environmental, not a test failure.