fix: profile import file upload, startup health check, sidebar scroll, node-pty fallback

- Change profile import from server path input to browser file upload (multipart)
- Fix startup script to wait for health check before opening browser
- Add overflow scroll with hidden scrollbar to sidebar nav
- Graceful degradation when node-pty fails to load (WSL compatibility)
- Remove rename button from profile cards
- Restrict profile name input to English letters, numbers, hyphens
- Use raw.githubusercontent.com URLs in README setup script

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

packages/client/src/components/layout/AppSidebar.vue

@@ -428,6 +428,13 @@ async function handleUpdate() {
   padding-top: 12px;
   flex-direction: column;
   gap: 4px;
+  overflow-y: auto;
+  min-height: 0;
+  scrollbar-width: none;
+
+  &::-webkit-scrollbar {
+    display: none;
+  }
 }
 
 .nav-item {