docs(core,data): complete Phases 0–2 of in-place card_game rewrite

Phase 0 – doc fixes (docs/card-game-integration.md):
- Correct stale "no serde" claim: upstream has serde at rev 99b49e62
- Correct take_from_foundation default description (Allowed, not Disallowed)
- Document schema v3→v4 migration and AnyInstruction strategy

Phase 1 – delegate check_win / check_auto_complete to upstream:
- Proptests verify semantic agreement with is_win() / is_win_trivial()
  across 256 random states before delegation

Phase 2 – schema v4 with v3 auto-migration:
- SavedInstruction mirror types kept as legacy compat module (needed by
  solitaire_data::ReplayMove and solitaire_wasm replay layer)
- klondike_adapter.rs: add comprehensive legacy-purpose doc comment
- proptest_tests.rs: add check_auto_complete/check_win semantic proofs
- storage.rs: rename round-trip test to v4, add v3-migrates-to-v4 test

Also track the rewrite plan (docs/in-place-card-game-rewrite-plan.md).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_core/src/proptest_tests.rs

@@ -1,3 +1,4 @@
+use card_game::Game;
 use klondike::{Foundation, KlondikePile, KlondikeInstruction, SkipCards, Tableau};
 use proptest::prelude::*;
 
@@ -107,6 +108,52 @@ fn apply_one_move(game: &mut GameState, move_idx: usize) -> bool {
 // ---------------------------------------------------------------------------
 
 proptest! {
+    /// `check_auto_complete()` and `is_win_trivial()` must agree on every
+    /// reachable game state.
+    ///
+    /// The upstream `Klondike::is_win_trivial()` checks that the stock pile
+    /// (both face-down and face-up halves) is completely empty AND that all
+    /// tableau columns have no face-down cards.  Ferrous `check_auto_complete()`
+    /// checks the same three conditions individually (stock empty, waste empty,
+    /// all tableau cards face-up).  This property guards against any semantic
+    /// drift between the two implementations so that delegating to upstream is
+    /// safe.
+    ///
+    /// If this property ever fails, `check_auto_complete()` must NOT be fully
+    /// replaced — the Ferrous conditions must be preserved and `is_win_trivial()`
+    /// used only as a supplementary guard.
+    #[test]
+    fn check_auto_complete_agrees_with_is_win_trivial(
+        seed in any::<u64>(),
+        draw_mode in draw_mode_strategy(),
+        actions in prop::collection::vec((any::<bool>(), 0usize..200), 0..30),
+    ) {
+        let mut game = GameState::new(seed, draw_mode);
+        apply_random_actions(&mut game, &actions);
+        prop_assert_eq!(
+            game.check_auto_complete(),
+            game.session().state().state().is_win_trivial(),
+            "check_auto_complete() disagreed with is_win_trivial() after {:?} actions",
+            actions.len(),
+        );
+    }
+
+    /// `check_win()` and `is_win()` must agree on every reachable game state.
+    #[test]
+    fn check_win_agrees_with_is_win(
+        seed in any::<u64>(),
+        draw_mode in draw_mode_strategy(),
+        actions in prop::collection::vec((any::<bool>(), 0usize..200), 0..30),
+    ) {
+        let mut game = GameState::new(seed, draw_mode);
+        apply_random_actions(&mut game, &actions);
+        prop_assert_eq!(
+            game.check_win(),
+            game.session().state().state().is_win(),
+            "check_win() disagreed with is_win()",
+        );
+    }
+
     /// All 52 card IDs must be present exactly once across every pile after
     /// any reachable sequence of draw + move_cards actions.
     ///