chore: untrack QA database, the local production plan, and a stray image

- .qa-data/qai.db{,-shm,-wal} was committed by an add -A during the cookie bug hunt; it holds throwaway accounts and sealed key blobs.
- plan-cxpaket.sqlplan (2.7 MB, real schema names) was committed one commit before the /plan-*.sqlplan ignore rule existed.
- an unrelated upscaled PNG from the working tree went in with the same add -A.
All four stay on disk and out of git; .ua/ is ignored too so generated graph data never sneaks in the same way.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitignore

@@ -13,6 +13,7 @@ next-env.d.ts
 # runtime data (sqlite)
 /data
 /.playwright-data
+.qa-data/
 
 # e2e artifacts
 /.auth
@@ -25,3 +26,6 @@ next-env.d.ts
 
 # real production plans dropped in for debugging stay out of git
 /plan-*.sqlplan
+
+# generated knowledge graph (regenerate with /understand)
+.ua/