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/SubscriptionPlans/Default.cshtml

@@ -0,0 +1,66 @@
+@using PlanTempus.Application.Features.Accounts.Models
+@model IEnumerable<PlanInfo>
+
+@{
+    var currentPlanKey = (string)ViewBag.CurrentPlanKey;
+}
+
+<swp-plan-grid>
+    @foreach (var plan in Model)
+    {
+        var isCurrent = plan.Key == currentPlanKey;
+        var cardClass = plan.Key switch
+        {
+            "enterprise" => isCurrent ? "enterprise current" : "enterprise",
+            _ => isCurrent ? "current" : ""
+        };
+
+        var badgeClass = isCurrent ? "current" : plan.BadgeClass;
+        var badgeText = isCurrent ? "Nuværende plan" : plan.BadgeText;
+        var badgeIcon = isCurrent ? "ph-check" : plan.BadgeIcon;
+
+        var buttonText = isCurrent
+            ? "Nuværende plan"
+            : plan.IsContactSales
+                ? "Kontakt salg"
+                : $"Skift til {plan.Name}";
+
+        var buttonClass = isCurrent
+            ? "secondary"
+            : plan.IsContactSales
+                ? "outline"
+                : "secondary";
+
+        <swp-plan-card class="@cardClass">
+            <swp-plan-badge class="@badgeClass">
+                <i class="ph @badgeIcon"></i>
+                @badgeText
+            </swp-plan-badge>
+            <swp-plan-name>@plan.Name</swp-plan-name>
+            <swp-plan-users>@plan.UserRange</swp-plan-users>
+            <swp-plan-price>
+                @if (plan.PricePerMonth.HasValue)
+                {
+                    <swp-plan-price-amount>@plan.PriceDisplay</swp-plan-price-amount>
+                    <swp-plan-price-period>kr/md</swp-plan-price-period>
+                }
+                else
+                {
+                    <swp-plan-price-amount>Kontakt os</swp-plan-price-amount>
+                }
+            </swp-plan-price>
+            <swp-plan-features>
+                @foreach (var feature in plan.Features)
+                {
+                    <swp-plan-feature>
+                        <i class="ph ph-check-circle"></i>
+                        @feature
+                    </swp-plan-feature>
+                }
+            </swp-plan-features>
+            <swp-plan-action>
+                <swp-btn class="@buttonClass">@buttonText</swp-btn>
+            </swp-plan-action>
+        </swp-plan-card>
+    }
+</swp-plan-grid>