chore: gitignore loose screenshots and commit docs asset

Ignore root-level landing-page-full.png, pain-section.png, and
north-star-advisor/ directory. Track docs/assets/too_many_tabs.png
alongside existing doc images.

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

Author: h4x0r

.gitignore

@@ -10,3 +10,7 @@ tarpaulin-report.json
 test-results/
 playwright-report/
 .vercel
+# Loose image assets (screenshots, mockups)
+landing-page-full.png
+pain-section.png
+north-star-advisor/