refactor(pricing): dynamic payment provider buttons with database-driven text

- Replace hardcoded provider-specific buttons with dynamic database-driven approach
  - Update getPlanProviders() to include display_name from payment_providers table
  - Simplify plan-card.blade.php with single if/else logic for all providers
  - Move trial button outside loop and comment for future implementation
  - Use "Pay with {display_name}" pattern for consistent button text
  - Maintain special handling for activation_key provider with disabled state

app/Livewire/Dashboard/Pricing.php

@@ -166,7 +166,9 @@ class Pricing extends Component
             ->join('payment_providers', 'plan_providers.provider', '=', 'payment_providers.name')
             ->where('payment_providers.is_active', true)
             ->orderBy('plan_providers.sort_order')
-            ->pluck('plan_providers.provider')
+            ->select('plan_providers.provider', 'payment_providers.display_name')
+            ->get()
+            ->keyBy('provider')
             ->toArray();
     }