Feature/toasts and error handling (#4496)

# Description of Changes

- Added error handling and toast notifications

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

frontend/tailwind.config.js

@@ -22,6 +22,42 @@ module.exports = {
           800: 'rgb(var(--gray-800) / <alpha-value>)',
           900: 'rgb(var(--gray-900) / <alpha-value>)',
         },
+        green: {
+          50: 'var(--color-green-50)',
+          100: 'var(--color-green-100)',
+          200: 'var(--color-green-200)',
+          300: 'var(--color-green-300)',
+          400: 'var(--color-green-400)',
+          500: 'var(--color-green-500)',
+          600: 'var(--color-green-600)',
+          700: 'var(--color-green-700)',
+          800: 'var(--color-green-800)',
+          900: 'var(--color-green-900)',
+        },
+        yellow: {
+          50: 'var(--color-yellow-50)',
+          100: 'var(--color-yellow-100)',
+          200: 'var(--color-yellow-200)',
+          300: 'var(--color-yellow-300)',
+          400: 'var(--color-yellow-400)',
+          500: 'var(--color-yellow-500)',
+          600: 'var(--color-yellow-600)',
+          700: 'var(--color-yellow-700)',
+          800: 'var(--color-yellow-800)',
+          900: 'var(--color-yellow-900)',
+        },
+        red: {
+          50: 'var(--color-red-50)',
+          100: 'var(--color-red-100)',
+          200: 'var(--color-red-200)',
+          300: 'var(--color-red-300)',
+          400: 'var(--color-red-400)',
+          500: 'var(--color-red-500)',
+          600: 'var(--color-red-600)',
+          700: 'var(--color-red-700)',
+          800: 'var(--color-red-800)',
+          900: 'var(--color-red-900)',
+        },
         // Custom semantic colors for app-specific usage
         surface: 'rgb(var(--surface) / <alpha-value>)',
         background: 'rgb(var(--background) / <alpha-value>)',