Add comprehensive UX/feature research for Gravl

Research compiled from Exa AI search covering:
- Market overview (2024-2032 projections)
- UX best practices and common mistakes
- User feedback from Reddit communities
- Competitor analysis (Strong, Hevy, FITBOD, etc.)
- Gamification strategies
- AI coaching trends
- Prioritized recommendations for Gravl

.planning/research/00-index.md

@@ -0,0 +1,28 @@
+# Gravl Research Index
+
+Research sammanställd 2026-02-15 via Exa AI Search.
+
+## Filer
+
+| Fil | Innehåll |
+|-----|----------|
+| [01-market-overview.md](01-market-overview.md) | Marknadsstorlek, trender, statistik |
+| [02-ux-best-practices.md](02-ux-best-practices.md) | UX-principer, design-misstag att undvika |
+| [03-user-feedback.md](03-user-feedback.md) | Reddit-analys, vad användare vill ha/hatar |
+| [04-competitor-analysis.md](04-competitor-analysis.md) | Strong, Hevy, FITBOD, JEFIT, m.fl. |
+| [05-gamification.md](05-gamification.md) | Gamification-mekanismer, motivation |
+| [06-ai-coaching.md](06-ai-coaching.md) | AI-coaching trends, conversational UI |
+| [07-recommendations.md](07-recommendations.md) | Konkreta rekommendationer för Gravl |
+| [08-sources.md](08-sources.md) | Alla källor och länkar |
+
+## Key Takeaways
+
+1. **70% churn inom 90 dagar** — UX är problemet, inte motivation
+2. **Offline-first är kritiskt** — Gym har dålig signal
+3. **Enkelhet vinner** — Strong/Hevy: minimal klick per set
+4. **AI ska vara transparent** — Visa VARFÖR, inte bara VAD
+5. **Conversational onboarding** — Dialog > formulär
+
+## Nästa steg
+
+Se [07-recommendations.md](07-recommendations.md) för prioriterad feature-lista.