Add discovery UI, hide NSFW setting, and pack progress

- New discovery components (ContentTile, ContentRow, CircularProgress)
- Refactor home screen with compact header and content tiles
- Add hide_nsfw profile setting for content filtering
- Add color column to categories table
- Track pack progress (answered/total questions)
- Update related stores and tests

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/mobile/app/(app)/packs/questions.tsx

@@ -496,6 +496,7 @@ export default function QuestionPacksScreen() {
                                     name: "Other",
                                     description: null,
                                     icon: "📁",
+                                    color: null,
                                     sort_order: 999,
                                     created_at: "",
                                     is_public: true