vscode: replace Netlify status bar with live OTA build status
Shows AC-OS oven build status in the VSCode status bar:
- Spinning icon + stage/percent during active builds
- Green check when idle (last build succeeded)
- Red error when last build failed
- Polls every 3s during builds, 30s when idle
- Click for details: Open Oven, Pull & Flash, or Refresh
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>