feat: Add Stripe payment integration and subscription management

- Add Stripe.net SDK for payment processing
- Implement StripeService with checkout sessions, customer portal, webhooks
- Implement SubscriptionService for quota management
- Add quota enforcement to CVCheckService
- Create Pricing, Billing, Settings pages
- Add checkout success/cancel pages
- Update Check and Dashboard with usage indicators
- Add ResetMonthlyUsageJob for billing cycle resets
- Add database migration for subscription fields

Plan tiers: Free (3 checks), Professional £49/mo (30), Enterprise £199/mo (unlimited)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

src/TrueCV.Infrastructure/DependencyInjection.cs

@@ -5,6 +5,7 @@ using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.DependencyInjection;
 using Polly;
 using Polly.Extensions.Http;
+using Stripe;
 using TrueCV.Application.Interfaces;
 using TrueCV.Infrastructure.Configuration;
 using TrueCV.Infrastructure.Data;
@@ -74,6 +75,16 @@ public static class DependencyInjection
         services.Configure<LocalStorageSettings>(
             configuration.GetSection(LocalStorageSettings.SectionName));
 
+        services.Configure<StripeSettings>(
+            configuration.GetSection(StripeSettings.SectionName));
+
+        // Configure Stripe API key
+        var stripeSettings = configuration.GetSection(StripeSettings.SectionName).Get<StripeSettings>();
+        if (!string.IsNullOrEmpty(stripeSettings?.SecretKey))
+        {
+            StripeConfiguration.ApiKey = stripeSettings.SecretKey;
+        }
+
         // Configure HttpClient for CompaniesHouseClient with retry policy
         services.AddHttpClient<CompaniesHouseClient>((serviceProvider, client) =>
             {
@@ -97,6 +108,8 @@ public static class DependencyInjection
         services.AddScoped<ICVCheckService, CVCheckService>();
         services.AddScoped<IUserContextService, UserContextService>();
         services.AddScoped<IAuditService, AuditService>();
+        services.AddScoped<IStripeService, StripeService>();
+        services.AddScoped<ISubscriptionService, Services.SubscriptionService>();
 
         // Register file storage - use local storage if configured, otherwise Azure
         var useLocalStorage = configuration.GetValue<bool>("UseLocalStorage");
@@ -111,6 +124,7 @@ public static class DependencyInjection
 
         // Register Hangfire jobs
         services.AddTransient<ProcessCVCheckJob>();
+        services.AddTransient<ResetMonthlyUsageJob>();
 
         return services;
     }