fix(ui): replace browser alerts with toast notifications

[SagitQuark]

Closes #227

Why this change?

The project already used react-hot-toast in several places, but a few admin workflows were still showing browser alert() dialogs when an action failed, this created an inconsistent user experience compared to the rest of the application.

This PR replaces those remaining alerts with toast notifications using the existing notification setup.

Changes made

• Replaced browser alert() calls with toast.error() notifications
• Updated menu-related error handling in MenusGrid.jsx
• Updated branch delete/restore error handling in BranchesGrid.jsx
• Reused the existing react-hot-toast implementation already used across the project
• Preserved existing backend error messages where available

Files updated

• src/components/admin/menu/menuCard/MenusGrid.jsx
• src/components/admin/store/branch/BranchesGrid.jsx

Testing

• Verified frontend compiles successfully after the changes
• Verified affected admin pages load correctly
• Confirmed all remaining alert() usages related to this issue have been removed

User-facing impact

Users will now see consistent toast notifications instead of browser alert popups when menu or branch actions failures