feat(engine): surface upstream move-type counters and replay seek

Two unused-for-free upstream card_game/klondike features:

- GameState now exposes the granular KlondikeStats counters
  (move_to_foundation_count, move_to_tableau_count,
  move_from_foundation_count, flip_up_count) and the win modal shows a
  quiet per-move-type recap line built from them (e.g. "21 to
  foundation - 14 tableau moves - 9 flips")
- wasm ReplayPlayer gains seek(step): clamped jump to any position,
  rewinding via a stored copy of the recorded deal instead of reparsing
  the replay JSON; replay.js Prev now uses it

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

solitaire_wasm/src/lib.rs

@@ -110,6 +110,9 @@ impl From<&(Card, bool)> for CardSnapshot {
 #[wasm_bindgen]
 pub struct ReplayPlayer {
     game: GameState,
+    /// The recorded deal before any instruction, kept so [`Self::seek_native`]
+    /// can rewind without reparsing the replay JSON.
+    initial: GameState,
     moves: Vec<KlondikeInstruction>,
     step_idx: usize,
 }
@@ -144,12 +147,30 @@ impl ReplayPlayer {
         // the current build maps seeds to deals.
         let (game, moves) = GameState::from_recording(&replay.recording, replay.seed, replay.mode);
         Ok(Self {
+            initial: game.clone(),
             game,
             moves,
             step_idx: 0,
         })
     }
 
+    /// Jump to `step` (clamped to the move count): the board state after
+    /// `step` moves have been applied. Rewinds by resetting to the stored
+    /// initial deal, then fast-forwards — a few hundred instruction
+    /// applications, microseconds in practice.
+    pub fn seek_native(&mut self, step: usize) -> Result<StateSnapshot, MoveError> {
+        let target = step.min(self.moves.len());
+        if target < self.step_idx {
+            self.game = self.initial.clone();
+            self.step_idx = 0;
+        }
+        while self.step_idx < target {
+            self.game.apply_instruction(self.moves[self.step_idx])?;
+            self.step_idx += 1;
+        }
+        Ok(self.snapshot())
+    }
+
     /// Apply the next move. Returns `Ok(None)` once the list is exhausted.
     pub fn step_native(&mut self) -> Result<Option<StateSnapshot>, MoveError> {
         if self.step_idx >= self.moves.len() {
@@ -236,6 +257,25 @@ impl ReplayPlayer {
         }
     }
 
+    /// Jump directly to `step` moves applied (clamped to the move count)
+    /// and return the snapshot there. Backwards seeks rewind to the
+    /// recorded deal and fast-forward, so any position is O(replay length)
+    /// at worst — no JSON reparse, no intermediate renders.
+    ///
+    /// Throws `"replay_desync"` if a recorded move is illegal during the
+    /// fast-forward (corrupt recording).
+    pub fn seek(&mut self, step: usize) -> Result<JsValue, JsValue> {
+        match self.seek_native(step) {
+            Ok(snap) => {
+                serde_wasm_bindgen::to_value(&snap).map_err(|e| JsValue::from_str(&e.to_string()))
+            }
+            Err(e) => {
+                log_replay_move_error(&e);
+                Err(JsValue::from_str("replay_desync"))
+            }
+        }
+    }
+
     /// Total number of moves the replay contains.
     pub fn total_steps(&self) -> usize {
         self.moves.len()
@@ -1062,6 +1102,57 @@ mod tests {
         assert_eq!(orig["stock"], repl["stock"], "stock deal must match");
     }
 
+    /// `seek` must land on exactly the state produced by stepping — both
+    /// forwards (fast-forward from the current position) and backwards
+    /// (rewind to the recorded deal, then fast-forward).
+    #[test]
+    fn seek_matches_stepping_in_both_directions() {
+        let mut game = SolitaireGame {
+            game: GameState::new_with_mode(51, DrawStockConfig::DrawOne, GameMode::Classic),
+        };
+        for _ in 0..24 {
+            let legal_moves = game.legal_moves_native();
+            if legal_moves.is_empty() {
+                break;
+            }
+            let idx = pick_move_index(&legal_moves).unwrap_or_default();
+            game.apply_legal_move_native(idx).expect("advance game");
+        }
+        let replay_json = game
+            .replay_export_native(60, "2026-07-10")
+            .expect("export replay");
+
+        let mut stepped = ReplayPlayer::from_json(&replay_json).expect("player A");
+        let mut seeker = ReplayPlayer::from_json(&replay_json).expect("player B");
+        let total = stepped.total_steps();
+        assert!(total >= 4, "test needs a few moves, got {total}");
+
+        // Forward: step A to k, seek B to k, compare snapshots.
+        let k = total / 2;
+        for _ in 0..k {
+            stepped.step_native().expect("step").expect("mid-replay");
+        }
+        let sought = seeker.seek_native(k).expect("seek forward");
+        assert_eq!(sought, stepped.snapshot(), "forward seek diverged at {k}");
+
+        // Backward: seek B to k - 2 and compare against a fresh stepper.
+        let back = k - 2;
+        let mut fresh = ReplayPlayer::from_json(&replay_json).expect("player C");
+        for _ in 0..back {
+            fresh.step_native().expect("step").expect("mid-replay");
+        }
+        let sought_back = seeker.seek_native(back).expect("seek backward");
+        assert_eq!(
+            sought_back,
+            fresh.snapshot(),
+            "backward seek diverged at {back}"
+        );
+
+        // Clamping: past-the-end seeks stop at the final state.
+        let end = seeker.seek_native(usize::MAX).expect("seek to end");
+        assert_eq!(end.step_idx, total);
+    }
+
     #[test]
     fn debug_api_autonomous_seed_batch_smoke() {
         for seed in 0_u64..128_u64 {