.gitignore keeps the bundle out of git but not out of _site, so the previous
commit published a megabyte-sized copy of the site inside itself — and because
design-bundle/ is generated *from* _site, a second build would have folded that
copy back in again.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01TL4uoCCvX2CqHWT8p3tLd7

diff --git a/_config.yml b/_config.yml
index db2f425..496aa4f 100644
--- a/_config.yml
+++ b/_config.yml
@@ -61,6 +61,10 @@ exclude:
   - test
   - vendor
   - lib
+  # Build artifacts. .gitignore does not exclude these from Jekyll, and
+  # design-bundle/ is built *from* _site, so leaving it in would fold a copy
+  # of the whole site back into the next build.
+  - design-bundle
   - .ruby-version
   - script