fix: replace all direct JSON.parse usages with safe parsing utilities

src/app/shared/theme-picker/theme-storage.service.ts

@@ -1,4 +1,5 @@
 import { Injectable, EventEmitter } from '@angular/core';
+import { safeParseObject } from 'app/core/utils/json';
 import { Theme } from './theme.model';
 import { ThemeManagerService } from './theme-manager.service';
 
@@ -19,7 +20,7 @@ export class ThemeStorageService {
   }
 
   getTheme(): Theme {
-    return JSON.parse(localStorage.getItem(this.themeStorageKey));
+    return safeParseObject<Theme | null>(localStorage.getItem(this.themeStorageKey), null);
   }
 
   clearTheme() {