style: Update default theme

toju-app/src/app/domains/theme/application/services/theme.service.ts

@@ -15,6 +15,7 @@ import {
   ThemeElementStyles
 } from '../../domain/models/theme.model';
 import {
+  BUILT_IN_THEME_PRESETS,
   DEFAULT_THEME_JSON,
   createDefaultThemeDocument,
   createDefaultThemeLayout,
@@ -137,6 +138,7 @@ export class ThemeService {
   readonly activeThemeName: Signal<string>;
   readonly knownAnimationClasses: Signal<string[]>;
   readonly isDraftDirty: Signal<boolean>;
+  readonly builtInPresets = BUILT_IN_THEME_PRESETS;
 
   private readonly documentRef = inject(DOCUMENT);
 
@@ -325,6 +327,26 @@ export class ThemeService {
     this.setStatusMessage(reason === 'shortcut' ? 'Theme reset to the default preset by shortcut.' : 'Theme reset to the default preset.');
   }
 
+  applyBuiltInPreset(name: string): boolean {
+    const preset = this.builtInPresets.find((builtInPreset) => builtInPreset.theme.meta.name === name || builtInPreset.key === name);
+
+    if (!preset) {
+      this.setStatusMessage('Built-in theme preset not found.');
+      return false;
+    }
+
+    const theme = structuredClone(preset.theme);
+    const result = validateThemeDocument(theme);
+
+    if (!result.valid || !result.value) {
+      this.setStatusMessage(result.errors[0] ?? 'Built-in theme preset could not be applied.');
+      return false;
+    }
+
+    this.commitTheme(result.value, stringifyTheme(result.value), `${result.value.meta.name} preset applied.`);
+    return true;
+  }
+
   handleGlobalShortcut(event: KeyboardEvent): boolean {
     const usesModifier = event.ctrlKey || event.metaKey;