docs: add research notes and scratch files

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

research/README.md

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+# Research Index
+
+All research documents in this directory. Most recent / most relevant listed first.
+
+| File | Topic | Date | Status |
+|---|---|---|---|
+| `padel-hall-economics.md` | Court construction costs, operator P&L, supplier margins, buyer segmentation | Feb 2026 | Current |
+| `competitor_pricing.md` | Competitor directory, pricing models, revenue archetypes (20+ platforms) | Feb 2026 | Current |
+| `market-research-padel-costs-2026.md` | Per-city court hire rates, rent, electricity, staff costs (DE/UK/US) | Feb 2026 | Current |
+| `state-of-padel-q1-2026/` | FIP reports 2024+2025, Playtomic Global Padel Report 2025 | Q1 2026 | Current |
+| `kfw/` | KfW loan documents and business plan templates | Feb 2026 | Current |
+| `additional-supply-side-idea.md` | Supplier-side product idea notes | Feb 2026 | Draft |
+| `padelnomics-master-strategy.md` | Original strategy doc | 2025 | **Superseded** — use MARKETING.md + PROJECT.md |
+| `PLAN.md` | Original roadmap | 2025 | **Superseded** |
+| `padel-daas-vision-plan.md` | Data-as-a-service vision | 2025 | **Superseded** |
+| `padel_daas_vision.md` | DaaS vision (older) | 2025 | **Superseded** |
+| `PadelDirectory.md` | Directory concept | 2025 | **Superseded** |
+| `padelnomics-strategy-stack.md` | Strategy stack | 2025 | **Superseded** |
+| `padelnomics_erp_for_padel_entrepreneurs_customer_journey.md` | Customer journey | 2025 | **Superseded** |
+| `padelnomics-jtbd-analysis.md` | JTBD analysis | 2025 | Background context only |
+| `padelnomics_lead_platform_discussion_summary.md` | Lead platform discussion | 2025 | Background context only |
+| `product_ideas.md` | Product ideas | 2025 | Background context only |
+| `sportstaettenrechner_quotes_2022.md` | Sportstaettenrechner 2022 lead volume data | 2022 | Historical data |
+
+## Key facts (quick reference)
+
+**Construction costs:**
+- 1 outdoor court (turnkey): €33,000–€80,000
+- 4 outdoor courts (commercial): €200,000–€350,000
+- 4-court indoor hall: €700,000–€1,200,000
+- 6-court indoor hall: €1,000,000–€1,700,000
+
+**Operator revenue:**
+- Germany: €4,000/court/month GMV (Playtomic 2025)
+- UK: €9,700/court/month GMV
+- 4-court outdoor: ~€224,000/year gross (padel-court.de)
+- EBITDA mature indoor club: 50–57%
+
+**Market growth:**
+- 7,187 new courts built globally in 2024
+- Germany: 507 courts (2024) → 827 (2025), +63% YoY
+- European construction market: ~€194M/year (2024)