Implement Homeworld mechanics through Caladan reinforcement checkpoint

Connect typed Homeworld custody, transport, battle, income, revival and Caladan reinforcement flows with private multiplayer recovery and controls. Preserve the optimized test workflow and keep unfinished rules modes gated. Verified with 3682 offline tests, typecheck, lint, production build and 40 HTTP tests; existing saved games remain unchanged.

game/terror-entry-receipt.ts

@@ -0,0 +1,65 @@
+import type { Game } from './engine';
+import { validLocation } from './board';
+import { HomeworldCustodyError } from './homeworld-custody';
+import { TERROR_STRONGHOLDS } from './moritani-terror';
+
+type TerrorEntry = NonNullable<Game['pendingTerrorEntry']>;
+
+/** Original public entry facts, independent of subsequent stage or population.
+ * This is a consistency receipt, not an authorization token or secret digest. */
+export function terrorEntrySignature(entry: TerrorEntry): string {
+  return JSON.stringify([
+    entry.token,
+    entry.entrant,
+    entry.territory,
+    entry.sector,
+    entry.amount,
+    entry.elite,
+    entry.cause,
+    entry.turn,
+    entry.phase,
+    entry.resume,
+    entry.ambassadorEvent ?? null,
+  ]);
+}
+
+/** Older saves without a receipt remain explicit legacy state. Never invent
+ * their original entry count from the destination's present occupants. */
+export function validateTerrorEntrySignature(entry: TerrorEntry): void {
+  if (entry.entrySignature === undefined) return;
+  if (
+    typeof entry.entrySignature !== 'string' ||
+    typeof entry.token !== 'string' ||
+    !entry.token ||
+    typeof entry.entrant !== 'string' ||
+    !entry.entrant ||
+    !TERROR_STRONGHOLDS.includes(entry.territory) ||
+    !Number.isSafeInteger(entry.sector) ||
+    !validLocation(entry.territory, entry.sector) ||
+    !Number.isSafeInteger(entry.amount) ||
+    entry.amount < 0 ||
+    !Number.isSafeInteger(entry.elite) ||
+    entry.elite < 0 ||
+    entry.elite > entry.amount ||
+    !Number.isSafeInteger(entry.turn) ||
+    entry.turn < 1 ||
+    !Number.isSafeInteger(entry.phase) ||
+    entry.phase < 0 ||
+    entry.phase > 8 ||
+    ![
+      'shipment',
+      'movement',
+      'guildTransport',
+      'advisor',
+      'wormRide',
+      'ambassador',
+    ].includes(entry.cause) ||
+    !['none', 'wormRide', 'ambassador'].includes(entry.resume) ||
+    (entry.ambassadorEvent !== undefined &&
+      (typeof entry.ambassadorEvent !== 'string' || !entry.ambassadorEvent)) ||
+    entry.entrySignature !== terrorEntrySignature(entry)
+  )
+    throw new HomeworldCustodyError(
+      'The saved Terror entry no longer matches its original public arrival receipt.',
+    );
+}