Priority 1: High (Polish & Ecosystem)

Important for v1.0.0 quality and ecosystem goals. Not blocking release, but recommended before ship.

1. Ensure All Widgets Have Examples

Status: Done

Verified that all widget types shipped with ratatui_ruby have at least one example showing how to use them.

Action: - [x] Check widget manifest against example inventory - [x] Create widget_canvas_demo, widget_center_demo, and widget_overlay_demo