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/homeworld-battle-rules.ts

@@ -0,0 +1,65 @@
+import { HOMEWORLD_CARDS, type HomeworldId } from './homeworld-cards';
+import type { FactionId } from './catalog';
+import type { HomeworldForces } from './homeworld-custody';
+
+/** The location adapter supplies the current face and exact native army.
+ * Occupation timing belongs to that adapter, not to the battle calculator. */
+export type HomeworldBattleRules = {
+  native: string;
+  card: HomeworldId;
+  side: 'high' | 'low';
+  nativeForces: HomeworldForces;
+};
+export type HomeworldExplosionLosses = {
+  player: string;
+  amount: number;
+  options: HomeworldForces[];
+};
+
+export function quoteHomeworldBattleRules(
+  location: string,
+  participants: readonly { id: string; faction: FactionId }[],
+  rules: HomeworldBattleRules,
+) {
+  const card = HOMEWORLD_CARDS.find((c) => c.id === rules?.card);
+  const native = participants.find((p) => p.id === rules?.native);
+  if (
+    !card ||
+    !native ||
+    native.faction !== card.faction ||
+    location !==
+      `homeworld:${card.faction}${card.id === 'salusa_secundus' ? ':salusa' : ''}` ||
+    !['high', 'low'].includes(rules.side) ||
+    !rules.nativeForces ||
+    typeof rules.nativeForces !== 'object' ||
+    Array.isArray(rules.nativeForces) ||
+    Object.keys(rules.nativeForces).length !== 2 ||
+    !['normal', 'elite'].every((key) =>
+      Object.hasOwn(rules.nativeForces, key),
+    ) ||
+    !Object.values(rules.nativeForces).every(
+      (n) => Number.isSafeInteger(n) && n >= 0,
+    ) ||
+    rules.nativeForces.normal + rules.nativeForces.elite > 20
+  )
+    throw new Error(
+      'The Homeworld battle needs its seated native, canonical card face and physical native army.',
+    );
+  const strength = card[rules.side].battleStrength;
+  const amount = Math.min(
+    strength,
+    rules.nativeForces.normal + rules.nativeForces.elite,
+  );
+  const options: HomeworldForces[] = [];
+  for (
+    let elite = Math.max(0, amount - rules.nativeForces.normal);
+    elite <= Math.min(amount, rules.nativeForces.elite);
+    elite++
+  )
+    options.push({ normal: amount - elite, elite });
+  return {
+    native: native.id,
+    strength,
+    explosion: { player: native.id, amount, options },
+  };
+}