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/stub.ts

@@ -38,6 +38,13 @@ export interface StubPayload {
    * path is covered by unit tests against applyTurnResult, not by the stub.
    */
   markers?: Array<{ id: string; type: string; name: string; regionKey: string; owner: string | null }>;
+  /**
+   * (v0.33.0, #56) Currently ACTIVE wars (`{ id, sides, aims? }`), emitted by
+   * the engine's user prompt. The stub ignores this field — it never declares
+   * or ends a war (see deterministicTurn), so the war path is covered by unit
+   * tests against applyTurnResult, not by the stub.
+   */
+  wars?: Array<{ id: string; sides: string[]; aims?: string[] }>;
 }
 
 function truncate(s: string, n: number): string {
@@ -81,6 +88,10 @@ function truncate(s: string, n: number): string {
  * (v0.32.0, #54) The stub likewise NEVER performs a non-military takeover
  * (it always returns `takeovers: []`) — the regime-rename path is covered by
  * unit tests only, keeping the e2e assertions untouched.
+ *
+ * (v0.33.0, #56) The stub likewise NEVER declares or ends a war (it always
+ * returns `wars: { declare: [], end: [] }`) — the war path is covered by unit
+ * tests only, keeping the e2e assertions untouched.
  */
 export function deterministicTurn(p: StubPayload): TurnResult {
   const state = p.state;
@@ -148,6 +159,7 @@ export function deterministicTurn(p: StubPayload): TurnResult {
     unowned: [], // the stub never creates no man's land (see doc comment)
     nationOps: [], // the stub never proposes nation ops (see doc comment)
     takeovers: [], // the stub never performs a takeover (see doc comment)
+    wars: { declare: [], end: [] }, // the stub never declares/ends wars (see doc comment)
     markers: { add: [], remove: [] }, // the stub never touches markers (see doc comment)
   };
 }