fix(plugin): Correct Claude marketplace source path

Update the Claude marketplace entry to use a schema-valid relative source path and add a regression test so invalid marketplace sources fail in the local suite. Also document the maintainer workflow used for stale PR metadata and fork-gated Actions runs.

Fixes #344

walkthrough.md

@@ -1,3 +1,12 @@
+# Maintenance Walkthrough - 2026-03-18
+
+- Fixed issue `#344` by correcting `.claude-plugin/marketplace.json` so the marketplace plugin entry uses `source: "./"` instead of `"."`, matching Claude Code's relative-path schema requirement for marketplace entries.
+- Added `tools/scripts/tests/claude_plugin_marketplace.test.js` and wired it into the local test suite so invalid marketplace `source` paths fail fast in CI/maintainer verification.
+- Merged PRs `#333`, `#336`, `#338`, `#343`, `#340`, and `#334` via GitHub squash merge after maintainer refresh of forked workflows and PR metadata.
+- Closed PR `#337` and PR `#342` as superseded by `#338`, then closed issue `#339` manually after confirming the accepted fix path; issue `#335` auto-closed from the merged PR body.
+- Left issue `#344` open with a triage comment, and left PR `#341` open with a blocking review comment because the submitted skill content is corrupted even though CI is green.
+- Documented a new maintainer edge case in `.github/MAINTENANCE.md`: forked runs in `action_required`, `pr-policy` failures caused by stale PR bodies, the REST API fallback when `gh pr edit` fails with the Projects Classic GraphQL error, and the need to `close`/`reopen` a PR when a plain rerun does not pick up updated metadata.
+
 # Maintenance Walkthrough - 2026-03-17
 
 - Synced `main` after the six merged community PRs and re-verified all forked PR workflows through GitHub before final release prep.