V2 Tauri integration (#3854)

# Description of Changes

Please provide a summary of the changes, including:

## Add PDF File Association Support for Tauri App

  ### 🎯 **Features Added**
  - PDF file association configuration in Tauri
  - Command line argument detection for opened files
  - Automatic file loading when app is launched via "Open with"
  - Cross-platform support (Windows/macOS)

  ### 🔧 **Technical Changes**
  - Added `fileAssociations` in `tauri.conf.json` for PDF files
  - New `get_opened_file` Tauri command to detect file arguments
  - `fileOpenService` with Tauri fs plugin integration
  - `useOpenedFile` hook for React integration
  - Improved backend health logging during startup (reduced noise)

  ### 🧪 **Testing**
See 
* https://v2.tauri.app/start/prerequisites/
*
[DesktopApplicationDevelopmentGuide.md](DesktopApplicationDevelopmentGuide.md)

  ```bash
  # Test file association during development:
  
  cd frontend
  npm install
  cargo tauri dev --no-watch -- -- "path/to/file.pdf"
  ```

 For production testing:
  1. Build: npm run tauri build
  2. Install the built app
  3. Right-click PDF → "Open with" → Stirling-PDF

  🚀 User Experience

- Users can now double-click PDF files to open them directly in
Stirling-PDF
- Files automatically load in the viewer when opened via file
association
  - Seamless integration with OS file handling

---

## 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/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/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/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/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: Connor Yoh <[email protected]>
Co-authored-by: James Brunton <[email protected]>
Co-authored-by: James Brunton <[email protected]>

frontend/src/desktop/hooks/useOpenedFile.ts

@@ -0,0 +1,47 @@
+import { useState, useEffect } from 'react';
+import { fileOpenService } from '@app/services/fileOpenService';
+
+export function useOpenedFile() {
+  const [openedFilePath, setOpenedFilePath] = useState<string | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    const checkForOpenedFile = async () => {
+      console.log('🔍 Checking for opened file...');
+      try {
+        const filePath = await fileOpenService.getOpenedFile();
+        console.log('🔍 fileOpenService.getOpenedFile() returned:', filePath);
+        
+        if (filePath) {
+          console.log('✅ App opened with file:', filePath);
+          setOpenedFilePath(filePath);
+          
+          // Clear the file from service state after consuming it
+          await fileOpenService.clearOpenedFile();
+        } else {
+          console.log('ℹ️ No file was opened with the app');
+        }
+
+      } catch (error) {
+        console.error('❌ Failed to check for opened file:', error);
+      } finally {
+        setLoading(false);
+      }
+    };
+
+    checkForOpenedFile();
+
+    // Listen for runtime file open events (abstracted through service)
+    const unlistenRuntimeEvents = fileOpenService.onFileOpened((filePath: string) => {
+      console.log('📂 Runtime file open event:', filePath);
+      setOpenedFilePath(filePath);
+    });
+
+    // Cleanup function
+    return () => {
+      unlistenRuntimeEvents();
+    };
+  }, []);
+
+  return { openedFilePath, loading };
+}