style: cargo fmt under rustfmt 1.9 and gate formatting in CI

The repo was formatted under an older stable; rustfmt 1.9 (Rust 1.95)
wraps signatures and call sites differently, so every touched file was
picking up unrelated formatting hunks. One mechanical pass, and a
'cargo fmt --check' step in the test workflow (same pinned 1.95.0
toolchain) so drift can't accumulate again.

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

solitaire_core/src/game_state.rs

@@ -439,10 +439,7 @@ impl GameState {
         self.session.history().len()
     }
 
-    fn cards_with_face(
-        cards: impl IntoIterator<Item = Card>,
-        face_up: bool,
-    ) -> Vec<(Card, bool)> {
+    fn cards_with_face(cards: impl IntoIterator<Item = Card>, face_up: bool) -> Vec<(Card, bool)> {
         cards.into_iter().map(|card| (card, face_up)).collect()
     }
 
@@ -507,8 +504,10 @@ impl GameState {
                 Self::cards_with_face(cards.iter().cloned(), true)
             }
             KlondikePile::Tableau(tableau) => {
-                let mut cards =
-                    Self::cards_with_face(state.tableau_face_down_cards(tableau).iter().cloned(), false);
+                let mut cards = Self::cards_with_face(
+                    state.tableau_face_down_cards(tableau).iter().cloned(),
+                    false,
+                );
                 cards.extend(Self::cards_with_face(
                     state.tableau_face_up_cards(tableau).iter().cloned(),
                     true,
@@ -823,9 +822,7 @@ impl GameState {
     ) -> Option<(KlondikePile, KlondikePile, usize)> {
         let state = self.session.state().state().state();
         match instruction {
-            KlondikeInstruction::RotateStock => {
-                Some((KlondikePile::Stock, KlondikePile::Stock, 1))
-            }
+            KlondikeInstruction::RotateStock => Some((KlondikePile::Stock, KlondikePile::Stock, 1)),
             KlondikeInstruction::DstFoundation(dst_foundation) => {
                 if matches!(dst_foundation.src, KlondikePile::Foundation(_)) {
                     return None;
@@ -928,10 +925,7 @@ impl GameState {
     ///
     /// Returns [`MoveError::RuleViolation`] if the instruction is illegal in the
     /// current position, or [`MoveError::GameAlreadyWon`] once the game is over.
-    pub fn apply_instruction(
-        &mut self,
-        instruction: KlondikeInstruction,
-    ) -> Result<(), MoveError> {
+    pub fn apply_instruction(&mut self, instruction: KlondikeInstruction) -> Result<(), MoveError> {
         if self.is_won() {
             return Err(MoveError::GameAlreadyWon);
         }
@@ -1296,12 +1290,13 @@ mod tests {
 
         game.take_from_foundation = false;
         assert!(!game.can_move_cards(&from, &to, 1));
-        assert!(
-            legal_pile_moves(&game)
-                .iter()
-                .all(|(f, t, _)| !matches!(f, KlondikePile::Foundation(_))
-                    || !matches!(t, KlondikePile::Tableau(_)))
-        );
+        assert!(legal_pile_moves(&game).iter().all(|(f, t, _)| !matches!(
+            f,
+            KlondikePile::Foundation(_)
+        ) || !matches!(
+            t,
+            KlondikePile::Tableau(_)
+        )));
         assert!(game.move_cards(from, to, 1).is_err());
     }
 
@@ -1360,9 +1355,18 @@ mod tests {
     fn budget_is_passed_through_not_clamped() {
         // This seed is Inconclusive at 1k states but Winnable at 5k — proving the
         // budget reaches the solver unchanged.
-        let easy = GameState::solve_fresh_deal(0xD1FF_0000_0000_0012, DrawStockConfig::DrawOne, 1_000, 1_000);
-        let medium =
-            GameState::solve_fresh_deal(0xD1FF_0000_0000_0012, DrawStockConfig::DrawOne, 5_000, 5_000);
+        let easy = GameState::solve_fresh_deal(
+            0xD1FF_0000_0000_0012,
+            DrawStockConfig::DrawOne,
+            1_000,
+            1_000,
+        );
+        let medium = GameState::solve_fresh_deal(
+            0xD1FF_0000_0000_0012,
+            DrawStockConfig::DrawOne,
+            5_000,
+            5_000,
+        );
         assert!(easy.is_err());
         assert!(matches!(medium, Ok(Some(_))));
     }

solitaire_core/src/lib.rs

@@ -13,7 +13,9 @@ pub mod scoring;
 // when decoding instructions to piles in `instruction_to_piles`) and do not
 // appear in any public method signature.
 pub use card_game::{Card, Deck, Rank, Session, SolveError, Suit};
-pub use klondike::{DrawStockConfig, Foundation, Klondike, KlondikeInstruction, KlondikePile, Tableau};
+pub use klondike::{
+    DrawStockConfig, Foundation, Klondike, KlondikeInstruction, KlondikePile, Tableau,
+};
 
 // Solvability check API (delegates to `card_game::Session::solve`); replaces the
 // former `solitaire_data::solver` wrapper module.

solitaire_core/src/proptest_tests.rs

@@ -41,13 +41,20 @@ fn all_cards(game: &GameState) -> Vec<Card> {
         );
     }
     for t in &tableaux {
-        cards.extend(game.pile(KlondikePile::Tableau(*t)).iter().map(|(c, _)| c.clone()));
+        cards.extend(
+            game.pile(KlondikePile::Tableau(*t))
+                .iter()
+                .map(|(c, _)| c.clone()),
+        );
     }
     cards
 }
 
 fn draw_mode_strategy() -> impl Strategy<Value = DrawStockConfig> {
-    prop_oneof![Just(DrawStockConfig::DrawOne), Just(DrawStockConfig::DrawThree)]
+    prop_oneof![
+        Just(DrawStockConfig::DrawOne),
+        Just(DrawStockConfig::DrawThree)
+    ]
 }
 
 /// Apply a sequence of random actions to a game, silently ignoring errors.