Derive Macro WidgetCommand 

#[derive(WidgetCommand)]

Typed command declarations for widget operations.

Generates a WidgetCommandEncode implementation that converts each variant to an (op, PropValue) pair for wire transport. Variant names become snake_case operation strings.

Uses the same variant forms as WidgetEvent:

• Unit: Reset produces ("reset", PropValue::Null)
• Single-field tuple: SetValue(f32) produces ("set_value", PropValue::F64(v))
• Named fields: SetRange { min: f32, max: f32 } produces ("set_range", PropValue::Object({min: ..., max: ...}))

Example

#[derive(WidgetCommand)]
enum GaugeCommand {
    /// Set gauge to a value immediately.
    SetValue(f32),
    /// Reset gauge to zero.
    Reset,
    /// Set the value range.
    SetRange { min: f32, max: f32 },
}

// Usage:
Command::widget("temp", GaugeCommand::SetValue(72.0))