fix: preserve ws:// vs wss:// scheme in URL normalization

frontend/src/App.tsx

@@ -436,9 +436,13 @@ function App(): JSX.Element {
     }
 
     let rawUrl = import.meta.env.CUSTOM_VITE_WS_URL || 'wss://excalidraw.forkless.com'
+    let scheme = 'wss://'
     try {
-      const parsed = new URL(rawUrl.startsWith('ws') ? rawUrl.replace(/^ws/, 'http') : rawUrl)
-      rawUrl = 'wss://' + parsed.host
+      let parseable = rawUrl
+      if (rawUrl.startsWith('ws://')) { scheme = 'ws://'; parseable = rawUrl.replace(/^ws:\/\//, 'http://') }
+      else if (rawUrl.startsWith('wss://')) { parseable = rawUrl.replace(/^wss:\/\//, 'https://') }
+      const parsed = new URL(parseable)
+      rawUrl = scheme + parsed.host
     } catch {
       // Bare hostname/IP — prepend wss://
       rawUrl = 'wss://' + rawUrl