docs: add backlog item 999.11 — marketing website (www vs app split)

.planning/ROADMAP.md

@@ -238,3 +238,11 @@ Plans:
 
 Plans:
 - [ ] TBD (promote with /gsd:review-backlog when ready)
+
+### Phase 999.11: Marketing Website (BACKLOG)
+**Goal**: Build a separate marketing/brand website (www.gearbox.de) distinct from the app (app.gearbox.de). Hero section with search bar, value proposition, feature highlights, how-it-works, social proof, and sign-up CTA. This is the public-facing front door — the first thing people see before they enter the app. The current discovery page is the in-app experience; this is the standalone website around it.
+**Requirements**: TBD
+**Plans**: TBD
+
+Plans:
+- [ ] TBD (promote with /gsd:review-backlog when ready)