feat(#56): War as a first-class state — declare/end ops, mutual-defense drag-in, relation sync

Promote the bare 'war' relation to a named War entity in GameState.wars:
- War: { id, sides[], declaredTurn, declaredDate?, aims?, status, front? }
- TurnResult.wars: { declare: WarDeclareOp[], end: WarEndOp[] }
- syncWarRelations: derive 'war' from active wars, fallback to 'hostile' on end
- Mutual-defense drag-in: belligerent allies added to sides (one level)
- Bare 'war' back-compat: never downgraded, never force-created
- Stub: empty wars (e2e unaffected); ~30 new unit tests

v0.33.0

shared/scenario.ts

@@ -453,6 +453,9 @@ export function worldDraftToGameState(
     // Seed AFTER the territories hold real region keys: each owned region gets
     // a copy of its owner's stats, so the derived aggregate equals them.
     regionStats: seedRegionStats(nations),
+    // (v0.33.0, #56) No wars on a fresh (dynamic) game; any preset-level `war`
+    // relation stays a bare/implicit one, not an entity (see syncWarRelations).
+    wars: [],
   };
   return state;
 }