Remove obsolete Livewire fuel search components and consolidate pricing tiers

- Delete unused Livewire Search test and fuel type select Blade component
- Move subscription webhook listener from EventServiceProvider to AppServiceProvider
- Add FUEL_TYPES global config to app layout for client-side use
- Add Billable trait to User model and include email_verified_at in fillable
- Implement monthly/annual cadence toggle with pricing display and smart CTA routing on homepage
- Update VerifyApiKeyMiddlewareTest to use e10 instead of petrol
- Refactor PollFuelPrices to auto-refresh stale stations based on last_seen_at
- Add incremental polling with cached timestamp and effective-start-timestamp param to FuelPriceService
- Normalize amenities/fuel_types from API objects to flat arrays, skip stations missing required fields
- Log response body on API failures in ApiLogger
- Default homepage sort to 'reliable' instead of 'price'

.env.example

@@ -69,6 +69,11 @@ FUELALERT_API_KEY=
 FRED_API_KEY=
 EIA_API_KEY=            # US EIA Open Data API key — register free at eia.gov/opendata
 
+STRIPE_KEY=
+STRIPE_SECRET=
+STRIPE_WEBHOOK_SECRET=
+CASHIER_CURRENCY=gbp
+
 STRIPE_PRICE_BASIC_MONTHLY=
 STRIPE_PRICE_BASIC_ANNUAL=
 STRIPE_PRICE_PLUS_MONTHLY=