Macro impl_adapter 

macro_rules! impl_adapter {
    (
        rect: $target_rect:ty,
        origin: $origin_ty:ty,
        convert_fn: $convert:expr,
        convert_at_fn: $convert_at:expr $(,)?
    ) => { ... };
}

Generates the 5 standard adapter functions for a renderer backend.

Each adapter converts panes::Rect into a renderer-specific rect type. The macro eliminates the duplicated convert, panels, panels_at, overlays, overlays_at pattern across adapter crates.

Parameters

• rect: target rect type (e.g. ratatui::layout::Rect, egui::Rect)
• origin: origin type for _at offset variants (must be Copy)
• convert_fn: expression &panes::Rect -> TargetRect
• convert_at_fn: expression (&panes::Rect, Origin) -> TargetRect