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

server/map.test.ts

@@ -52,6 +52,8 @@ const state: GameState = {
   markers: [],
   // (v0.28, #46) the map is ownership-only; the region-stats table is unused here.
   regionStats: {},
+  // (v0.33.0, #56) the map is ownership-only; wars are unused here.
+  wars: [],
 };
 
 // The RegionMap built from the fixture: the authoritative region key → owner source.