chore: re-ignore packages/exoagent (local experiment clone)

Un-ignoring packages/ for the capnweb submodule surfaced it.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: ryanrasti

.gitignore

@@ -12,3 +12,5 @@ site/public/demo.ts.static
 site/public/typegres.js
 site/public/typegres.d.ts
 .claude/
+# local clone of ~/src/exoagent (pre-existing experiment; not part of the build)
+packages/exoagent/