Remove local workspace files from public repo

Remove .mcp.json and backlog/ from tracking. These are local
development workflow files that should not be in the public repo.
Add them to .gitignore alongside CLAUDE.local.md.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: happi

.gitignore

@@ -32,3 +32,6 @@ site
 /vendor/
 /.bundle/
 /Gemfile.lock
+CLAUDE.local.md
+.mcp.json
+/backlog/