chore(showcase): git-ignore transient checklist-test driver scripts

A browser-lane checklist-test runner must write its Playwright driver inside
examples/app-showcase so require('@playwright/test') resolves through pnpm's
nesting — a script under /tmp cannot. Runners delete theirs on completion, but
a run in flight legitimately has them on disk, where they show as untracked in
a checkout several agents share.

Ignoring .qa-*.cjs/.mjs keeps git status honest during a run without inviting
anyone to commit a throwaway driver.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YD9f6FYyMraUWYeJf53V43

Author: claude

examples/app-showcase/.gitignore

@@ -2,3 +2,11 @@
 # Playwright smoke artifacts
 test-results/
 playwright-report/
+
+# Transient checklist-test driver scripts. A browser-lane runner must write its
+# Playwright driver INSIDE this app so `require('@playwright/test')` resolves
+# through pnpm's nesting (a script in /tmp cannot). Runners delete these when
+# they finish, but a run in flight legitimately has them on disk — ignoring the
+# pattern keeps `git status` honest for the other agents sharing this checkout.
+.qa-*.cjs
+.qa-*.mjs