feat(ui): Terrakotta Nacht replaces Soft, smooth menus and sliding notes on phones

- dark counterpart of Terrakotta; Soft users move to it
- add tailwindcss-animate: the existing animate-in/fade/slide classes now
  run; menus zoom in, sheets slide up, notes slide in on phones
- no animations with reduced motion

chore(release): v0.13.0

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/lib/__tests__/theme.test.ts

@@ -65,3 +65,21 @@ describe('custom themes', () => {
     expect(document.documentElement.classList.contains('dark')).toBe(true);
   });
 });
+
+describe('built-in themes', () => {
+  beforeEach(() => localStorage.clear());
+
+  it('moves removed themes to their successors', () => {
+    localStorage.setItem('mindsift_active_theme', 'soft');
+    expect(getActiveTheme()).toBe('terracotta-night');
+    localStorage.setItem('mindsift_active_theme', 'high-contrast');
+    expect(getActiveTheme()).toBe('dark');
+  });
+
+  it('treats Terrakotta as a light theme and Terrakotta Nacht as dark', () => {
+    setActiveTheme('terracotta');
+    expect(document.documentElement.classList.contains('dark')).toBe(false);
+    setActiveTheme('terracotta-night');
+    expect(document.documentElement.classList.contains('dark')).toBe(true);
+  });
+});

frontend/src/lib/theme.ts

@@ -58,14 +58,14 @@ export const AVAILABLE_THEMES: ThemeOption[] = [
     isRounded: true,
   },
   {
-    id: 'soft',
-    name: 'Soft Slate (Abgerundet)',
-    subtitle: 'Schiefer-Blau mit weichen Radien (10px)',
-    file: 'src/themes/theme-soft.css',
-    previewBg: '#0f172a',
-    previewPanel: '#1e293b',
-    previewAccent: '#3b82f6',
-    previewText: '#f8fafc',
+    id: 'terracotta-night',
+    name: 'Terrakotta Nacht (Glut)',
+    subtitle: 'Espresso, Creme & glühende Terrakotta (12px)',
+    file: 'src/themes/theme-terracotta-night.css',
+    previewBg: '#17110d',
+    previewPanel: '#211913',
+    previewAccent: '#e8794a',
+    previewText: '#f3e8da',
     isRounded: true,
   },
   {
@@ -188,8 +188,12 @@ function load(key: string): string | null {
   }
 }
 
+// Removed themes and their successors
+const RETIRED_THEMES: Record<string, ThemeId> = { soft: 'terracotta-night', 'high-contrast': 'dark' };
+
 export function getActiveTheme(): ThemeId {
-  const saved = load(THEME_STORAGE_KEY);
+  const stored = load(THEME_STORAGE_KEY);
+  const saved = stored && RETIRED_THEMES[stored] ? RETIRED_THEMES[stored] : stored;
   if (saved && AVAILABLE_THEMES.some((t) => t.id === saved)) return saved;
   if (saved && isCustomThemeId(saved) && load(CUSTOM_CSS_CACHE_KEY)) return saved;
   return 'dark';