Fix marketplace plugin source so claude.ai can sync the repo

[gal-cstk]

What this fixes

.claude-plugin/marketplace.json lists the plugin with "source": ".". claude.ai (Customize > Plugins > Add marketplace, which also feeds Cowork and Claude Code synced plugins) rejects that form: adding contentstack/contentstack-agent-skills fails with "Marketplace sync failed. Check the repository URL and try again."

claude.ai requires relative plugin sources to start with ./ (org sync rules). This PR changes the one value:

-      "source": ".",
+      "source": "./",

How it was tested

• Forked the repo, made only this change, and added the fork as a marketplace on claude.ai. It synced and listed Contentstack skills for install. The unchanged upstream repo fails with the error above.
• claude plugin validate . passes, so Claude Code (/plugin marketplace add) keeps working.

Why it matters

With claude.ai able to sync the repo, people can add it once on their account and get these skills in claude.ai, Cowork and Claude Code, auto-updating when this repo changes. Today the only claude.ai route is uploading a zip, which goes stale.

One related note, not changed here: plugin.json pins "version": "0.1.0". Claude Code decides whether to update an installed plugin by comparing that version, so new commits don't reach existing installs until the version is bumped. Worth bumping it with each release (or removing it so the commit SHA is used).

🤖 Generated with Claude Code

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[timbenniks-contentstack]

Thanks @gal-cstk for tracking this down, and for testing it on a fork! The "./" source is now in #21, the combined 0.2.0 release PR. Following your note, the manifests also get a version bump (0.2.0), and the validator now checks that every manifest has the same version. You're credited in the PR description. Closing in favour of #21.