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/tailwind.config.js

@@ -85,6 +85,7 @@ export default {
       },
       fontFamily: {
         sans: [
+          'Inter Variable',
           'Inter',
           'system-ui',
           '-apple-system',