Add BeanFlows MVP: coffee analytics dashboard, API, and web app

- Fix pipeline granularity: add market_year to cleaned/serving SQL models
- Add DuckDB data access layer with async query functions (analytics.py)
- Build Chart.js dashboard: supply/demand, STU ratio, top producers, YoY table
- Add country comparison page with multi-select picker
- Replace items CRUD with read-only commodity API (list, metrics, countries, CSV)
- Configure BeanFlows plan tiers (Free/Starter/Pro) with feature gating
- Rewrite public pages for coffee market intelligence positioning
- Remove boilerplate items schema, update health check for DuckDB
- Add test suite: 139 tests passing (dashboard, API, billing)

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

web/.env.example

@@ -0,0 +1,30 @@
+# App
+APP_NAME=BeanFlows
+SECRET_KEY=change-me-generate-a-real-secret
+BASE_URL=http://localhost:5000
+DEBUG=true
+ADMIN_PASSWORD=admin
+
+# Database
+DATABASE_PATH=data/app.db
+DUCKDB_PATH=../local.duckdb
+
+# Auth
+MAGIC_LINK_EXPIRY_MINUTES=15
+SESSION_LIFETIME_DAYS=30
+
+# Email (Resend)
+RESEND_API_KEY=
+EMAIL_FROM=hello@example.com
+
+
+# Paddle
+PADDLE_API_KEY=
+PADDLE_WEBHOOK_SECRET=
+PADDLE_PRICE_STARTER=
+PADDLE_PRICE_PRO=
+
+
+# Rate limiting
+RATE_LIMIT_REQUESTS=100
+RATE_LIMIT_WINDOW=60