fix(web): rebuild Bevy canvas WASM; add SolitaireGame interactive API

Grey screen fix (canvas_bg.wasm):
- Rebuilt Bevy WASM from refactored solitaire_core that removes the
  per-game KlondikeAdapter field from GameState. The old binary was
  built with wasm-opt -Oz; the large adapter allocation pattern appears
  to trigger an over-aggressive wasm-opt optimisation that corrupts
  Bevy's render pipeline, causing a permanent grey screen on /play.
- build_wasm.sh: change wasm-opt -Oz → -O2. Speed-optimised level avoids
  the size-focused transforms that miscompile Bevy's deep render stacks.

solitaire_core refactoring:
- game_state.rs: remove adapter: KlondikeAdapter field; use static
  KlondikeAdapter::config_for() instead of a per-instance allocation.
  Gate test_pile_state behind #[cfg(feature = "test-support")] so
  production builds carry no test-only heap state.
  Add instruction_history() public accessor (delegates to saved_moves()).
- card.rs: add Card::new(), face_up(), face_down() const constructors
  for more ergonomic test and wasm code.
- pile.rs, solver.rs: cargo fmt.

solitaire_wasm interactive API:
- lib.rs: add SolitaireGame wasm-bindgen struct with draw(), move_cards(),
  undo(), auto_complete_step(), serialize(), from_saved() — the full
  player-action surface used by game.js.
  Add DebugSnapshot, DebugMove, DebugInvariantReport structs and
  debug_snapshot(), debug_legal_moves(), debug_apply_move_json()
  methods for e2e test automation (window.__FERROUS_DEBUG__ bridge).
  Add replay_moves() to export the current game as a Replay v2 payload.
- solitaire_wasm.js + solitaire_wasm_bg.wasm: rebuilt with new API.

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

solitaire_core/Cargo.toml

@@ -4,6 +4,10 @@ version.workspace = true
 license.workspace = true
 edition.workspace = true
 
+[features]
+default = []
+test-support = []
+
 [dependencies]
 serde     = { workspace = true }
 thiserror = { workspace = true }