decide which tools from the standalone 3D viewer to bring over to 3D viewer in Pattern Editor

[mbreiser]

the views, FOV, positions, screenshots, etc.

[mbreiser]

Implemented in commits b93da82, 95e714e, 114d23f.

Features added to the Pattern Editor 3D viewer:

• 10 view presets — 6 external (Top Down, Bottom Up, From N/E/S/W) + 4 internal fly views (Fly → N/E/S/W)
• Zoom controls — labeled +/− buttons
• FOV slider — 30°–120° range with 60° and 120° preset buttons
• Screenshot button — captures only the 3D preview panel (📷 Screenshot)
• Arena Stats overlay — collapsible panel showing columns, total panels, inner radius, arena height, total LEDs, azimuth/vertical resolution, pixel dimensions

Bug fixes:

• 3D geometry now fully rebuilds on arena config change (tracked via threeViewerArenaConfig)
• Controls work with default arena (no need to explicitly select first)
• Panel number toggle preserves camera position (no reset to top-down)
• Cache-busting added for GitHub Pages deployment