V2 Replace Google Fonts icons with locally bundled Iconify icons (#4283)

# Description of Changes

This PR refactors the frontend icon system to remove reliance on
@mui/icons-material and the Google Material Symbols webfont.

🔄 Changes

Introduced a new LocalIcon component powered by Iconify.
Added scripts/generate-icons.js to:
Scan the codebase for used icons.
Extract only required Material Symbols from
@iconify-json/material-symbols.
Generate a minimized JSON bundle and TypeScript types.
Updated .gitignore to exclude generated icon files.
Replaced all <span className="material-symbols-rounded"> and MUI icon
imports with <LocalIcon> usage.
Removed material-symbols CSS import and related font dependency.
Updated tsconfig.json to support JSON imports.
Added prebuild/predev hooks to auto-generate the icons.

✅ Benefits

No more 5MB+ Google webfont download → reduces initial page load size.
Smaller install footprint → no giant @mui/icons-material dependency.
Only ships the icons we actually use, cutting bundle size further.
Type-safe icons via auto-generated MaterialSymbolIcon union type.

Note most MUI not included in this update since they are low priority
due to small SVG sizing (don't grab whole bundle)


---

## 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.

---------

Co-authored-by: a <a>

frontend/src/global.d.ts

@@ -4,4 +4,15 @@ declare module "../components/PageEditor";
 declare module "../components/Viewer";
 declare module "*.js";
 declare module '*.module.css';
-declare module 'pdfjs-dist';
+declare module 'pdfjs-dist';
+
+// Auto-generated icon set JSON import
+declare module '../assets/material-symbols-icons.json' {
+  const value: {
+    prefix: string;
+    icons: Record<string, any>;
+    width?: number;
+    height?: number;
+  };
+  export default value;
+}