chore: update .gitignore to exclude database, images, and artifacts

Remove database.sqlite from tracking and add database/database.sqlite,
images/, blackalgo.jpg, and nul to .gitignore.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

.gitignore

@@ -29,3 +29,7 @@ yarn-error.log
 /.claude/settings.local.json
 /.windsurf
 /LandingPageApp
+database/database.sqlite
+images/
+blackalgo.jpg
+nul