rlvgl-core

This crate contains the runtime abstractions that underpin every widget and backend used in rlvgl.

Currently implemented pieces:

• Widget trait defining drawing and event callbacks
• WidgetNode tree for hierarchical composition
• Event enum for basic input
• Renderer trait for target-agnostic drawing
• Style struct with builder for widget appearance

These APIs are early and will evolve as more widgets and backends come online.