brand(art): add 12 generated illustrations to drawable-nodpi; gitignore brand source art

Phase 0 of wiring the generated brand art (full-res per request). Adds A1 pairing,
A2 answer-history, A3 challenges header, A4 memory-lane capsule, A5 date-match
empty+success, A6 bucket-list, A8 messages, A9 quiet-hours, A10 past-games,
A11 privacy-recovery, A12 account-deletion to res/drawable-nodpi. Source working art
(docs/brand/{generated-art,sources,exports}) gitignored — only app copies committed.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.gitignore

@@ -77,3 +77,9 @@ docs/brand/asset-system.md
 docs/brand/visual-identity.md
 docs/brand/asset-system.md
 ClaudeBrandingReview.md
+ClaudeQAPlan.md
+
+# Brand source/working art (heavy; the wired copies live in app/src/main/res)
+docs/brand/generated-art/
+docs/brand/sources/
+docs/brand/exports/