Point template gallery sources at eve-examples

[cmpadden]

Summary

The Chat and Slack templates shown in the docs gallery now live under vercel/eve-examples, but the gallery manifest still syncs and links to their former standalone repositories.

Update those manifest entries to use the eve-examples subdirectories. Confirm that generated source snapshots, pinned revision links, and rendered README links continue to work for monorepo-backed templates.

[e0-gh-vercel-connect]

Triaged vercel/eve#1906 as p2, build, enhancement. No duplicate found. The old repos still resolve, so this is docs maintenance rather than a current breakage. The fix is already open in PR #1907.