Theme asset lazyload

[anarchyysm]

Problem

Goal: only theme.conf loads at boot; icons/, fonts/ and animations/ load on demand.
Estimated effort: 1–2 days

Proposed Solution

• Implement tos_theme_load_icon(screen_name, icon_name) — tries themes/{theme}/icons/{icon}.png, silent fallback to /assets/icons/
• Implement tos_theme_load_font(font_name) — tries themes/{theme}/fonts/, fallback to firmware default font
• Implement tos_theme_load_animation(anim_name) — tries themes/{theme}/animations/, fallback to default animation
• Ensure fallback is always silent — no missing asset should freeze or display an error on screen
• Integrate tos_theme_load_icon() in screens that use icons: screens/home/, screens/menu/
• Integrate tos_theme_load_animation() in the boot screen: screens/boot/
• Test: theme with no icons/ folder — confirm default icons are used with no errors
• Test: theme with partial icons/ folder (only some PNGs) — confirm missing icons fall back individually
• Test: measure boot time with and without lazyload to confirm the gain

Use Case

No response

Alternatives Considered

No response