chore(git): ignore the nested distrib worktree

distrib/ is a second checkout of this repository on the distrib branch
(git worktree add -b distrib distrib main); its .git file would otherwise
show up as an untracked embedded repository on main.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_011xpLSeYKKHX6o16jzYLgZv

.gitignore

@@ -47,6 +47,9 @@ logs/
 jdeploy-bundle/
 jdeploy/
 node_modules/
+# `git worktree add -b distrib distrib main`: a second checkout of this repository on the distrib branch,
+# nested here for convenience. Never part of main's own tree.
+/distrib/
 
 
 # graft's local graph cache — regenerable, not committed (run `graft build`).