fix frontend board mapping, game-over handling, and WASM-4

- fix Xform yx and add a shared view-aware board_position helper
- add GTK automatic game-over, restart, status, and multi-capture selection
- pin librsvg to the 2.60 series to match GTK4/glib 0.20
- add WASM orientation, undo/redo/new/flip controls, and winner overlay
- replace WASM crown images with canvas paths and remove dead files/deps
- make WASM-4 playable with mouse input, crowns, winner handling, and correct mapping
- move the WASM-4 release profile to the workspace root
- clean up frontend dead code and update the README

rdraught-gtk/examples/ai_debugger.rs

@@ -1,7 +1,5 @@
 use glib::ExitCode;
-use rdraught::{DraughtsBoard, DraughtsGame, Move, Piece, Player, Position};
-use rdraught_gtk::run;
-use std::collections::HashMap;
+use rdraught::{DraughtsGame, Move};
 use std::mem::size_of;
 
 fn main() -> ExitCode {