Initial implementation of Options Sidekick

Full-stack iOS options trading assistant:
- Python FastAPI backend with SQLite, APScheduler (15-min position monitor),
  APNs push notifications, and yfinance market data integration
- Signal engine: IV Rank (rolling HV proxy), SMA-50/200, swing-based
  support/resistance, earnings detection, signal strength scoring and
  noise-resistant SHA hash for change detection
- Recommendation engine: covered call and cash-secured put strike/expiry
  selection across 0DTE, 1DTE, weekly, and monthly horizons
- REST API: /devices, /portfolio, /recommendations, /positions, /signals, /alerts
- iOS SwiftUI app (iOS 17+): dashboard, recommendations, trades, portfolio,
  and alerts tabs with push notification deep-linking
- Unit + integration tests for signal engine and API layer

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

backend/.env.example

@@ -0,0 +1,7 @@
+DATABASE_URL=sqlite:///./app.db
+APNS_KEY_PATH=./AuthKey_XXXXXXXXXX.p8
+APNS_KEY_ID=XXXXXXXXXX
+APNS_TEAM_ID=XXXXXXXXXX
+APNS_BUNDLE_ID=com.yourname.options-sidekick
+APNS_USE_SANDBOX=true
+RECOMMENDATION_THROTTLE_MINUTES=5