Add full cross-platform path support

- Added automatic volume path translation in deployment (deploy.js)
- Updated FileBrowser template to use /opt/ instead of hard-coded E:/
- Migrated self-updater.js to use centralized platformPaths module
- Updated UI placeholders to use platform-neutral paths (/media/)
- All paths now automatically adapt to Windows or Linux at runtime via process.platform detection

status/js/app-selector.js

@@ -104,7 +104,7 @@
 
             <!-- Path input with browse button -->
             <div class="flex-row-gap">
-              <input type="text" id="deploy-media-path" placeholder="E:/Movies, E:/TVShows"
+              <input type="text" id="deploy-media-path" placeholder="/media/Movies, /media/TVShows"
                      class="input-flex" style="font-size: 0.95rem;" />
               <button type="button" id="browse-media-btn" style="padding: 10px 16px; background: var(--accent); color: white; border: none; border-radius: 6px; cursor: pointer; font-weight: 500; white-space: nowrap;">
                 📂 Browse
@@ -465,7 +465,7 @@
     if (appTemplate.mediaMount) {
       mediaPathSection.style.display = 'block';
       mediaPathInput.value = '';
-      mediaPathInput.placeholder = 'E:/Movies, E:/TVShows or click Browse';
+      mediaPathInput.placeholder = '/media/Movies, /media/TVShows or click Browse';
 
       // Fetch detected mounts from existing media servers
       const detectedMountsContainer = document.getElementById('detected-mounts-container');