[Feature] Generate and publish multi-resolution simulator UI screenshots

[3rdIteration]

Summary

Add a CI workflow step to generate UI screenshots from the simulator for all supported boards and publish them as a single artifact for visual regression review.

Motivation

We need a consistent way to verify UI layout/scaling across resolutions (including small and landscape screens) on every CI run.

Scope

• Run simulator screenshot tour in CI for:
  • wave_4b (720x720)
  • wave_35 (320x480)
  • wave_5 (720x1280)
• Use offscreen rendering and --screenshot-tour <output_dir>
• Store outputs in per-board folders named:
  • _x/
• Ensure each board folder includes the full tour set (01–13 PNGs)
• Upload one artifact named ui-screenshots
• Keep existing CI jobs/behavior unchanged

[odudex]

Idea LGTM, it's a very useful tool for quick UI bug catching.