Fix: Revert to reliable estimated rates (open-source API unavailable)

- Remove non-functional open-source Royal Mail API integration
- Revert to proven estimated rates based on Royal Mail standard pricing
- Royal Mail doesn't provide direct real-time pricing API
- Merchants expected to build their own rate matrix using OBA rates
- Estimated rates are reliable and can be manually updated as needed

Checkout now uses consistent, working shipping rates.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/lib/royalmail-shipping.ts

@@ -44,18 +44,12 @@ export async function getRoyalMailShippingQuotes(
   const weightKg = weightGrams / 1000;
   const isInternational = !UK_COUNTRIES.includes(destinationCountry.toUpperCase());
 
-  try {
-    console.log('🚀 Fetching Royal Mail rates from open-source API...');
-    const rates = await fetchOpenSourceRoyalMailRates(weightGrams, destinationCountry);
-    console.log('✅ Royal Mail API SUCCESS - Got', rates.length, 'shipping options');
-    return rates;
-  } catch (error) {
-    console.error('❌ Royal Mail API FAILED:', error instanceof Error ? error.message : String(error));
-    console.log('📦 Falling back to estimated rates');
-    // Fall back to estimated rates if API fails
+  // Use calculated estimated rates based on Royal Mail's standard pricing
+  // Note: Royal Mail doesn't provide a direct real-time pricing API
+  // Instead, they expect you to build your own rate matrix using their OBA rates
+  console.log('📦 Using Royal Mail estimated rates (based on standard pricing)');
   return calculateEstimatedRates(weightKg, isInternational, destinationCountry);
 }
-}
 
 function calculateEstimatedRates(
   weightKg: number,
@@ -114,59 +108,6 @@ function calculateEstimatedRates(
   return quotes;
 }
 
-/**
- * Fetch Royal Mail shipping rates using open-source Royal Mail Price API
- * This uses the community-maintained Royal Mail price matrix
- */
-async function fetchOpenSourceRoyalMailRates(
-  weightGrams: number,
-  destinationCountry: string
-): Promise<ShippingQuote[]> {
-  try {
-    const isInternational = !UK_COUNTRIES.includes(destinationCountry.toUpperCase());
-    const endpoint = 'https://royalmail-api.herokuapp.com/prices';
-
-    // Call open-source Royal Mail API
-    const response = await fetch(endpoint, {
-      method: 'POST',
-      headers: {
-        'Content-Type': 'application/json',
-      },
-      body: JSON.stringify({
-        weight_grams: Math.ceil(weightGrams),
-        destination_country: destinationCountry.toUpperCase(),
-        service_type: isInternational ? 'international' : 'domestic',
-      }),
-    });
-
-    if (!response.ok) {
-      throw new Error(`Royal Mail API error: ${response.status} ${response.statusText}`);
-    }
-
-    const data = (await response.json()) as {
-      services?: Array<{
-        name: string;
-        price: number;
-        estimated_days: number;
-      }>;
-    };
-
-    if (!data.services || data.services.length === 0) {
-      throw new Error('No services returned from Royal Mail API');
-    }
-
-    // Transform API response to our format
-    return data.services.map((service) => ({
-      service: service.name,
-      price: Math.ceil(service.price), // Ensure it's in pence
-      estimatedDays: service.estimated_days,
-      isInternational: isInternational,
-    }));
-  } catch (error) {
-    console.error('Error fetching Royal Mail rates:', error);
-    throw error;
-  }
-}
 
 /**
  * Format price from pence to pounds string