chore(deps): migrate to Bevy 0.17

- Event/EventReader/EventWriter renamed to Message/MessageReader/MessageWriter
- add_event → add_message for all 67 call sites
- ScrollPosition changed to tuple struct ScrollPosition(Vec2)
- CursorIcon import moved from bevy::winit::cursor to bevy::window
- WindowResolution::from((f32,f32)) removed — use (u32,u32) tuple
- World::send_event → World::write_message in test code

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/cursor_plugin.rs

@@ -12,8 +12,7 @@
 //!   The tint is cleared to default the frame the drag ends.
 
 use bevy::prelude::*;
-use bevy::window::{PrimaryWindow, SystemCursorIcon};
-use bevy::winit::cursor::CursorIcon;
+use bevy::window::{CursorIcon, PrimaryWindow, SystemCursorIcon};
 use solitaire_core::card::Suit;
 use solitaire_core::game_state::{DrawMode, GameState};
 use solitaire_core::pile::PileType;