add gstack skill symlinks, graphify skill, and gitignore updates

Track all gstack-provided skill symlinks (autoplan, browse, qa, etc.)
and the graphify skill. Add .claude/, graphify-out/, .ctx7-cache/ to
gitignore to exclude local/generated files from the repo.

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

.gitignore

@@ -3,6 +3,13 @@
 # Symlink created by link.sh (GStack submodule target)
 skills/gstack
 
+# Local project config (per-machine, not shared)
+.claude/
+
+# Generated outputs
+graphify-out/
+.ctx7-cache/
+
 # Install logs
 install-*.log