Adds suppliers feature to application

Introduces comprehensive suppliers management with mock data, localization, and UI components

Implements:
- Suppliers page with data table
- Localization for Danish and English
- Search and filtering functionality
- Responsive table design
- Mock data for initial population

PlanTempus.Application/wwwroot/css/suppliers.css

@@ -0,0 +1,70 @@
+/**
+ * Suppliers - Page Styling
+ *
+ * Feature-specific styling only.
+ * Reuses:
+ *   - swp-sticky-header, swp-header-content, swp-page-container (page.css)
+ *   - swp-stats-row.cols-4, swp-stat-card (stats.css)
+ *   - swp-action-bar, swp-search-input (components.css)
+ *   - swp-data-table, swp-status-badge, swp-empty-state (components.css)
+ *   - swp-btn (components.css)
+ */
+
+/* ===========================================
+   SUPPLIER TABLE (uses swp-data-table from components.css)
+   =========================================== */
+swp-card.suppliers-list {
+  padding: 0;
+  overflow: hidden;
+}
+
+/* Table columns: Leverandør(1fr) | Kontakt(150px) | Produkter(80px) | Sidste(120px) | Status(100px) */
+swp-card.suppliers-list swp-data-table {
+  grid-template-columns: minmax(200px, 1fr) 150px 80px 120px 100px;
+}
+
+swp-card.suppliers-list swp-data-table-header,
+swp-card.suppliers-list swp-data-table-row {
+  padding: 0 var(--spacing-10);
+}
+
+swp-card.suppliers-list swp-data-table-header swp-data-table-cell {
+  padding-top: var(--spacing-5);
+  padding-bottom: var(--spacing-5);
+}
+
+swp-card.suppliers-list swp-data-table-row {
+  cursor: pointer;
+}
+
+swp-card.suppliers-list swp-data-table-cell {
+  padding: var(--spacing-5) 0;
+}
+
+/* Supplier cell (name + city) */
+swp-supplier-cell {
+  display: flex;
+  flex-direction: column;
+  gap: 2px;
+}
+
+swp-supplier-name {
+  font-weight: var(--font-weight-medium);
+  color: var(--color-text);
+}
+
+swp-supplier-city {
+  font-size: var(--font-size-sm);
+  color: var(--color-text-secondary);
+}
+
+/* Products column (center + mono) */
+swp-card.suppliers-list swp-data-table-row swp-data-table-cell:nth-child(3) {
+  font-family: var(--font-mono);
+  text-align: center;
+}
+
+/* Last order column (muted) */
+swp-card.suppliers-list swp-data-table-row swp-data-table-cell:nth-child(4) {
+  color: var(--color-text-secondary);
+}