feat: add incremental trie lookup API and Deck::without_cards

- Add TrieCursor struct for partial Supersonic LUT trie traversal
- Add init_lookup/advance_lookup/finish_* methods for 5/6/7-card incremental eval
- Add raw_init/raw_advance/raw_finish_* zero-cost API (no depth tracking)
- Add Deck::without_cards() for constructing remaining decks
- Re-export TrieCursor from evaluator module
- Add comprehensive tests for all new APIs
- Update .gitignore for docs/REFERENCES.md

holdem_core/src/deck.rs

@@ -210,6 +210,42 @@ impl Deck {
     pub fn cards(&self) -> &[Card] {
         &self.cards
     }
+
+    /// Creates a new deck excluding the specified cards.
+    ///
+    /// Useful for constructing a "remaining deck" that omits known cards
+    /// (hero's hole cards, board cards) — typically resulting in a 45–47 card
+    /// deck for enumeration-based equity calculations.
+    ///
+    /// # Examples
+    ///
+    /// ```rust
+    /// use holdem_core::{Deck, Card};
+    /// use std::str::FromStr;
+    ///
+    /// let deck = Deck::new();
+    /// let excluded = vec![
+    ///     Card::from_str("As").unwrap(),
+    ///     Card::from_str("Kh").unwrap(),
+    /// ];
+    /// let remaining = deck.without_cards(&excluded);
+    /// assert_eq!(remaining.remaining(), 50);
+    /// ```
+    ///
+    /// # Panics
+    ///
+    /// This method does not panic.
+    pub fn without_cards(&self, excluded: &[Card]) -> Deck {
+        use std::collections::HashSet;
+        let exclude_set: HashSet<Card> = excluded.iter().copied().collect();
+        let cards: Vec<Card> = self
+            .cards
+            .iter()
+            .copied()
+            .filter(|c| !exclude_set.contains(c))
+            .collect();
+        Deck { cards }
+    }
 }
 
 impl Default for Deck {