test(core): possible_instructions Foundation→Tableau coverage

Add two tests verifying that possible_instructions includes
Foundation→Tableau moves when take_from_foundation is enabled,
and excludes them when it is disabled.

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

solitaire_core/src/game_state.rs

@@ -1680,6 +1680,29 @@ mod tests {
         );
     }
 
+    #[test]
+    fn possible_instructions_includes_foundation_to_tableau_when_enabled() {
+        // Reuse the Foundation→Tableau board setup (Foundation(0): A♠,2♠; Tableau(0): 3♥).
+        let g = setup_take_from_foundation_game();
+        assert!(g.take_from_foundation);
+        let moves = g.possible_instructions();
+        assert!(
+            moves.contains(&(PileType::Foundation(0), PileType::Tableau(0), 1)),
+            "possible_instructions must include Foundation→Tableau when take_from_foundation is on; got {moves:?}"
+        );
+    }
+
+    #[test]
+    fn possible_instructions_excludes_foundation_to_tableau_when_disabled() {
+        let mut g = setup_take_from_foundation_game();
+        g.take_from_foundation = false;
+        let moves = g.possible_instructions();
+        assert!(
+            !moves.iter().any(|(from, _, _)| matches!(from, PileType::Foundation(_))),
+            "possible_instructions must not include any Foundation source when take_from_foundation is off; got {moves:?}"
+        );
+    }
+
     // --- P2: waste multi-card move must be rejected ---
 
     #[test]