feat(theme): add Polarized and Suri purple dark themes

frontend/src/lib/theme.ts

@@ -68,6 +68,28 @@ export const AVAILABLE_THEMES: ThemeOption[] = [
     previewText: '#f8fafc',
     isRounded: true,
   },
+  {
+    id: 'polarized',
+    name: 'Polarized (Ultraviolet)',
+    subtitle: 'Tiefdunkles Obsidian mit elektrischem Violett (0px)',
+    file: 'src/themes/theme-polarized.css',
+    previewBg: '#0d0b14',
+    previewPanel: '#151221',
+    previewAccent: '#a855f7',
+    previewText: '#f5f3ff',
+    isRounded: false,
+  },
+  {
+    id: 'suri',
+    name: 'Suri (Velvet Dusk)',
+    subtitle: 'Warmes Mitternachts-Pflaume mit samtiger Orchidee (10px)',
+    file: 'src/themes/theme-suri.css',
+    previewBg: '#130f1a',
+    previewPanel: '#1e1728',
+    previewAccent: '#b86bf8',
+    previewText: '#fbf7ff',
+    isRounded: true,
+  },
 ];
 
 export const isCustomThemeId = (id: ThemeId) => id.startsWith(CUSTOM_THEME_PREFIX);