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.lock

@@ -7032,6 +7032,7 @@ dependencies = [
 name = "solitaire_core"
 version = "0.1.0"
 dependencies = [
+ "card_game",
  "klondike",
  "rand 0.9.4",
  "serde",