Trim unused LVGL features

[zjwhitehead]

Summary

• Disable unused LVGL widgets, including arc, button, chart, menu, table, textarea, spinner, and their composite widgets.
• Disable the unused flex and grid layout engines.
• Keep the widgets used by the controller UI enabled: bar, image, label, line, LED, animation support, and the default theme.

Why

LVGL's default theme references enabled widget classes, so unused widgets were retained in the firmware even though the application never creates them. Disabling those features at compile time removes their code without changing the rendered UI or runtime behavior.

Impact

The isolated debug firmware build uses 1,210,653 bytes of flash, approximately 56 KB less than the 1,267,085-byte baseline. RAM usage remains effectively unchanged.

Validation

• Production ESP32-S3 PlatformIO build passed.
• 28 version-independent LVGL screenshot golden tests passed in an isolated worktree.
• Splash tests were excluded from this focused PR because the base branch's references still contain v8.0 while the firmware reports v8.1; that test-maintenance fix is being kept separate.