fix(workspace): single scroll area, drag cleanup, thin note titles with bundled Inter

- the workspace fills the window; only the note scrolls (also on phones, where the
  sideways scroll area used to scroll on its own)
- clear drag state on dragend, calmer sidebar toggle when collapsed
- ship Inter as variable font, light and larger note titles; header shows the
  title only after the big title scrolled away and stays one row on phones
- main builds show the package version without -dev

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

frontend/src/main.tsx

@@ -2,6 +2,8 @@ import React from 'react';
 import ReactDOM from 'react-dom/client';
 import App from './App';
 import { MobileActionProvider } from './context/MobileActionContext';
+// Inter ships with the app (no external font service); the variable font covers all weights
+import '@fontsource-variable/inter';
 import './index.css';
 
 ReactDOM.createRoot(document.getElementById('root')!).render(