feat(core): card/pile conversion utils and GameMode-aware scoring (steps 2-prep, 5)

Step 2 prep — card_game dep + type-conversion utilities:
- Add card_game = "0.3.0" (registry Quaternions) to workspace + core
- suit_to_kl / suit_from_kl, rank_to_kl / rank_from_kl
- card_to_kl (drops id, Deck1), card_from_kl (reconstructs stable id
  from Clubs-first suit×13+rank ordering matching deck.rs)
- Ready to wire into KlondikeState pile projection once upstream
  adds KlondikeState::from_piles()

Step 5 — GameMode-aware scoring in the adapter:
- score_for_move_with_mode, score_for_flip_with_mode (return 0 in Zen)
- apply_undo_score (static, handles Zen + −15 penalty + clamp)
- score_for_recycle_with_mode (return 0 in Zen)
- game_state.rs: all inline GameMode::Zen checks replaced with
  adapter calls; adapter is now the single source of truth for
  "what score does this action give in this mode"

192 tests pass; clippy -D warnings clean.

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

Cargo.toml

@@ -38,6 +38,7 @@ solitaire_sync   = { path = "solitaire_sync" }
 solitaire_data   = { path = "solitaire_data" }
 solitaire_engine = { path = "solitaire_engine" }
 klondike         = { version = "0.2.0", registry = "Quaternions" }
+card_game        = { version = "0.3.0", registry = "Quaternions" }
 
 # Bevy with `default-features = false` to avoid the unused
 # `bevy_audio → rodio + symphonia + cpal 0.15 + alsa 0.9` chain.