Update zapier description to evergreen wording

[BenMcGit]

Summary

Replace the "8,000+ apps" wording on the zapier marketplace entry with phrasing that doesn't reference a specific count. The Zapier app catalogue has already grown past the current number (Zapier's own README says 9,000+), and it will keep growing — every bump requires a registry PR to update a number that's stale again within months.

The new wording mirrors the count-free style used by neighboring partner entries (Common Room, Box, Intercom) and stays accurate as the catalogue grows.

What changes

Field	Before	After
description	Connect 8,000+ apps to your AI workflow. Discover, enable, and execute Zapier actions directly from your client.	Connect your AI to thousands of apps and tens of thousands of pre-built actions through Zapier. Search, automate, and take action across your stack — directly from your AI client.

No other fields touched — name, displayName, category, source, and homepage are unchanged.

Verification

• jq . .claude-plugin/marketplace.json > /dev/null — JSON parses
• Description still accurately describes plugin behavior (discover, enable, execute Zapier actions)
• Plugin SHA unchanged, so the policy scan should hit the cached verdict and pass quickly