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/core/components/rightRail/RightRailFooterExtensions.tsx

@@ -0,0 +1,7 @@
+interface RightRailFooterExtensionsProps {
+  className?: string;
+}
+
+export function RightRailFooterExtensions(_props: RightRailFooterExtensionsProps) {
+  return null;
+}

frontend/src/core/components/shared/RightRail.tsx

@@ -13,6 +13,7 @@ import { Tooltip } from '@app/components/shared/Tooltip';
 import { ViewerContext } from '@app/contexts/ViewerContext';
 import { useSignature } from '@app/contexts/SignatureContext';
 import LocalIcon from '@app/components/shared/LocalIcon';
+import { RightRailFooterExtensions } from '@app/components/rightRail/RightRailFooterExtensions';
 
 import { useSidebarContext } from '@app/contexts/SidebarContext';
 import { RightRailButtonConfig, RightRailRenderContext, RightRailSection } from '@app/types/rightRail';
@@ -224,6 +225,8 @@ export default function RightRail() {
         </div>
 
         <div className="right-rail-spacer" />
+
+        <RightRailFooterExtensions className="right-rail-footer" />
       </div>
     </div>
   );

frontend/src/core/components/shared/rightRail/RightRail.css

@@ -17,6 +17,9 @@
   align-items: center;
   gap: 0.75rem;
   padding: 1rem 0.5rem;
+  width: 100%;
+  height: 100%;
+  flex: 1;
 }
 
 .right-rail-section {

frontend/src/core/pages/HomePage.tsx

@@ -20,14 +20,21 @@ import { useFilesModalContext } from "@app/contexts/FilesModalContext";
 import AppConfigModal from "@app/components/shared/AppConfigModal";
 import ToolPanelModePrompt from "@app/components/tools/ToolPanelModePrompt";
 import AdminAnalyticsChoiceModal from "@app/components/shared/AdminAnalyticsChoiceModal";
+import { useHomePageExtensions } from "@app/pages/useHomePageExtensions";
 
 import "@app/pages/HomePage.css";
 
 type MobileView = "tools" | "workbench";
 
+interface HomePageProps {
+  openedFile?: File | null;
+}
 
-export default function HomePage() {
+export default function HomePage({ openedFile }: HomePageProps = {}) {
   const { t } = useTranslation();
+
+  // Extension hook for desktop-specific behavior (e.g., file opening)
+  useHomePageExtensions(openedFile);
   const {
     sidebarRefs,
   } = useSidebarContext();

frontend/src/core/pages/useHomePageExtensions.ts

@@ -0,0 +1,10 @@
+import { useEffect } from 'react';
+
+/**
+ * Extension point for HomePage behaviour.
+ * Core version does nothing.
+ */
+export function useHomePageExtensions(_openedFile?: File | null) {
+  useEffect(() => {
+  }, [_openedFile]);
+}

frontend/src/core/services/apiClient.ts

@@ -1,10 +1,11 @@
 import axios from 'axios';
 import { handleHttpError } from '@app/services/httpErrorHandler';
 import { setupApiInterceptors } from '@app/services/apiClientSetup';
+import { getApiBaseUrl } from '@app/services/apiClientConfig';
 
 // Create axios instance with default config
 const apiClient = axios.create({
-  baseURL: import.meta.env.VITE_API_BASE_URL || '/',
+  baseURL: getApiBaseUrl(),
   responseType: 'json',
 });
 

frontend/src/core/services/apiClientConfig.ts

@@ -0,0 +1,7 @@
+/**
+ * Get the base URL for API requests.
+ * Core version uses simple environment variable.
+ */
+export function getApiBaseUrl(): string {
+  return import.meta.env.VITE_API_BASE_URL || '/';
+}