Adds account management and subscription features

Introduces new account pages for managing subscriptions, payment methods, and invoice history

Includes:
- Subscription plan selection view
- Payment method display component
- Invoice history table
- Account page layout and styling

Updates main layout to include new CSS files for account management

PlanTempus.Application/Features/Account/Components/PaymentMethod/Default.cshtml

@@ -0,0 +1,40 @@
+<swp-payment-card>
+    <swp-payment-method>
+        <swp-payment-icon>
+            <i class="ph ph-credit-card"></i>
+        </swp-payment-icon>
+        <swp-payment-info>
+            <swp-payment-type>Visa</swp-payment-type>
+            <swp-payment-number>**** **** **** 4582</swp-payment-number>
+        </swp-payment-info>
+        <swp-btn class="secondary sm">
+            <i class="ph ph-pencil"></i>
+            Skift
+        </swp-btn>
+    </swp-payment-method>
+
+    <swp-payment-detail>
+        <swp-payment-label>Betalingsfrekvens</swp-payment-label>
+        <swp-payment-value>Månedlig</swp-payment-value>
+    </swp-payment-detail>
+
+    <swp-payment-detail>
+        <swp-payment-label>Næste betaling</swp-payment-label>
+        <swp-payment-value class="highlight">1. februar 2026</swp-payment-value>
+    </swp-payment-detail>
+
+    <swp-payment-detail>
+        <swp-payment-label>Beløb</swp-payment-label>
+        <swp-payment-value>599,00 kr</swp-payment-value>
+    </swp-payment-detail>
+
+    <swp-payment-detail>
+        <swp-payment-label>Kortudløb</swp-payment-label>
+        <swp-payment-value>08/2027</swp-payment-value>
+    </swp-payment-detail>
+
+    <swp-btn class="outline" style="margin-top: var(--spacing-2);">
+        <i class="ph ph-arrows-clockwise"></i>
+        Skift til årlig betaling (spar 15%)
+    </swp-btn>
+</swp-payment-card>