fix: improve update system UX and macOS compatibility

Update System Improvements:
- Fix duplicate update popups by disabling legacy updater.js
- Add skip button to update popup (shows after 30s, on error, or after download)
- Add macOS-specific handling with manual download as primary option
- Add missing open-download-page IPC handler
- Add missing unblockInterface() method to properly clean up after popup close
- Add quitAndInstallUpdate alias in preload for compatibility
- Remove pulse animation when download completes
- Fix manual download button to show correct status and close popup
- Sync player name to settings input after first install

Client Patcher Cleanup:
- Remove server patching code (server uses pre-patched JAR from CDN)
- Simplify to client-only patching
- Remove unused imports (crypto, AdmZip, execSync, spawn, javaManager)
- Remove unused methods (stringToUtf8, findAndReplaceDomainUtf8)
- Move localhost dev code to backup file for reference

Code Quality Fixes:
- Fix duplicate DOMContentLoaded handlers in install.js
- Fix duplicate checkForUpdates definition in preload.js
- Fix redundant if/else in onProgressUpdate callback
- Fix typo "Harwadre" -> "Hardware" in preload.js

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

GUI/index.html

@@ -882,7 +882,7 @@
     <script src="js/i18n.js"></script>
     <script type="module" src="js/settings.js"></script>
     <script type="module" src="js/update.js"></script>
-    <script src="js/updater.js"></script>
+    <!-- updater.js disabled - using update.js instead which has skip button and macOS handling -->
 </body>