fix: overhaul examples mobile view

[kpal81xd]

Description

Mobile examples browser overhaul.

Area	Change
Layout	Adds shared mobile layout state, dock-driven panels, and resizable portrait/landscape drawers.
Dock	Keeps portrait on the bottom dock and moves landscape to a right rail with even spacing.
Panels	Splits Examples, Source, Controls, and Info into separate mobile panels.
Runtime	Adds iframe loading/error overlays, MiniStats/device sync, zoom blocking, and panel resize handling.
Controls	Fixes mobile sizing and cleanup for the 2D blend tree control.

Manual Tests

Case	Result
Portrait	Checked bottom dock and mobile sheets.
Landscape	Checked right rail, drawer spacing, resize, fullscreen, and rotation.

Preview

Portrait	Portrait	Portrait

Landscape

Checklist

• I have read the contributing guidelines
• My code follows the project coding standards
• This PR focuses on a single change