fix: use proxy paths for filebrowser URLs to avoid mixed content on HTTPS

Mock backend lan-address now uses localhost so hostname replacement works
correctly. CloudFolder external URLs use origin-relative proxy paths.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

neode-ui/mock-backend.js

@@ -587,7 +587,7 @@ const mockData = {
       'backup-progress': null,
       'update-progress': null,
     },
-    'lan-address': '192.168.1.100',
+    'lan-address': 'localhost',
     'tor-address': 'archydemox7k3pnw4hv5qz2jcbr6dwefys3ockqzf4mzjlvxot2ioad.onion',
     unread: 3,
     'wifi-ssids': ['Home-5G', 'Archipelago-Mesh', 'Neighbors-Open'],
@@ -640,7 +640,7 @@ function staticApp({ id, title, version, shortDesc, longDesc, license, state, la
       'interface-addresses': {
         main: {
           'tor-address': torHost ? `${torHost}.onion` : `${id}.onion`,
-          'lan-address': lanPort ? `http://192.168.1.100:${lanPort}` : '',
+          'lan-address': lanPort ? `http://localhost:${lanPort}` : '',
         },
       },
       status: state,