chore(core): remove dead card_to_kl / suit_to_kl / rank_to_kl helpers

These were scaffolded for a future KlondikeState::from_piles() path
that never materialised. card_from_kl (used by sync_piles_from_session)
is retained; suit_from_kl / rank_from_kl are narrowed to pub(crate).

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

solitaire_core/src/klondike_adapter.rs

@@ -13,7 +13,7 @@
 //! - Move validation via klondike's rule engine (step 2).
 //! - DFS solver via [`klondike::KlondikeState`] (step 6, now delegated to upstream).
 
-use card_game::{Card as KlCard, Deck as KlDeck, Rank as KlRank, Suit as KlSuit};
+use card_game::{Card as KlCard, Rank as KlRank, Suit as KlSuit};
 use klondike::{
     DrawStockConfig, DstFoundation, DstTableau, Foundation, KlondikeConfig, KlondikeInstruction,
     KlondikePile, KlondikePileStack, MoveFromFoundationConfig, ScoringConfig, SkipCards, Tableau,
@@ -185,26 +185,10 @@ impl KlondikeAdapter {
     }
 }
 
-// ── Type-conversion utilities (Step 2 — pile mapping) ────────────────────
+// ── Type-conversion utilities ─────────────────────────────────────────────
-//
-// These are used to translate between solitaire_core's Card/PileType and the
-// card_game / klondike types when projecting KlondikeState into the pile
-// snapshot that the engine reads.  A live KlondikeState shadow requires an
-// upstream `KlondikeState::from_piles()` constructor; these utilities are
-// ready to wire in once that's available.
-
-/// Convert our [`crate::card::Suit`] to [`card_game::Suit`].
-pub fn suit_to_kl(suit: crate::card::Suit) -> KlSuit {
-    match suit {
-        crate::card::Suit::Clubs    => KlSuit::Clubs,
-        crate::card::Suit::Diamonds => KlSuit::Diamonds,
-        crate::card::Suit::Hearts   => KlSuit::Hearts,
-        crate::card::Suit::Spades   => KlSuit::Spades,
-    }
-}
 
 /// Convert [`card_game::Suit`] back to our [`crate::card::Suit`].
-pub fn suit_from_kl(suit: KlSuit) -> crate::card::Suit {
+pub(crate) fn suit_from_kl(suit: KlSuit) -> crate::card::Suit {
     match suit {
         KlSuit::Clubs    => crate::card::Suit::Clubs,
         KlSuit::Diamonds => crate::card::Suit::Diamonds,
@@ -213,27 +197,14 @@ pub fn suit_from_kl(suit: KlSuit) -> crate::card::Suit {
     }
 }
 
-/// Convert our [`crate::card::Rank`] to [`card_game::Rank`].
-pub fn rank_to_kl(rank: crate::card::Rank) -> KlRank {
-    KlRank::new(rank.value()).expect("rank value 1-13 always maps to a valid KlRank")
-}
-
 /// Convert [`card_game::Rank`] back to our [`crate::card::Rank`].
-pub fn rank_from_kl(rank: KlRank) -> crate::card::Rank {
+pub(crate) fn rank_from_kl(rank: KlRank) -> crate::card::Rank {
     crate::card::Rank::RANKS
         .into_iter()
         .find(|r| r.value() == rank as u8)
         .expect("KlRank 1-13 always maps to a valid Rank")
 }
 
-/// Convert our [`crate::card::Card`] to a [`card_game::Card`] (Deck1, same suit/rank).
-///
-/// The `id` field is dropped; use [`card_to_kl`] only when the klondike engine
-/// needs to evaluate the card's logical identity, not its animation entity.
-pub fn card_to_kl(card: &crate::card::Card) -> KlCard {
-    KlCard::new(KlDeck::Deck1, suit_to_kl(card.suit), rank_to_kl(card.rank))
-}
-
 /// Convert a [`card_game::Card`] back to our [`crate::card::Card`], assigning
 /// a stable `id` derived from the suit and rank (0–51, Clubs-first ordering).
 ///