polish: address final-review minors before merge

Four single-line cleanups flagged by per-task and final reviewers:

- types.ts:95 — playerProfiles JSDoc said "ignored" but engine merges AI keys.
  Reword to match actual behaviour (the spec prose at §4.2 already documents
  this as "merged but Setup UI doesn't surface them").
- ai/dispatcher.test.ts:69 — tighten /human/i to /planAi.*human/i so the test
  fails if the planAi guard is removed (previously dispatch.ts's existing
  throw also matched /human/i).
- ai/lookahead.test.ts:88 — drop redundant duplicate planAi() call inside the
  not.toThrow wrapper. The next-line assertion already exercises the call.
- ai/lookahead.test.ts:94 — let s → const s; s is never reassigned.

160/160 tests still green. Typecheck clean.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: emp3thy

src/engine/types.ts

@@ -92,7 +92,7 @@ export interface SealedOrders {
 
 export interface GameConfig {
   startPopOverride?: Partial<Record<LeaderId, number>>;
-  /** Per-game name/country overrides for player slots. Keys should be 'player1'..'player5'; entries for AI leaders are ignored. Setup screen populates this from user input. */
+  /** Per-game name/country overrides for player slots. Keys should be 'player1'..'player5'; entries for AI leaders are merged but the Setup UI does not surface them. Setup screen populates this from user input. */
   playerProfiles?: Partial<Record<LeaderId, { name?: string; country?: string }>>;
   dominanceThreshold: number;
   fastPlay: boolean;

tests/engine/ai/dispatcher.test.ts

@@ -66,6 +66,6 @@ describe('planAi dispatcher', () => {
       difficulty: 'normal',
       seed: 'planAi-human',
     });
-    expect(() => planAi(s, 'player1')).toThrow(/human/i);
+    expect(() => planAi(s, 'player1')).toThrow(/planAi.*human/i);
   });
 });

tests/engine/ai/lookahead.test.ts

@@ -85,13 +85,12 @@ describe('bestTargetByLookahead', () => {
     s.leaders.player1.population = 8;
     s.leaders.player1.stockpile.shields = 0;
     // No lastOrders[player1] populated. Should not throw, should pick a target.
-    expect(() => planAi(s, 'chump')).not.toThrow();
     const orders = planAi(s, 'chump');
     expect(orders.find((o) => o.kind === 'launch')).toBeDefined();
   });
 
   it('mixed cast with history: lookahead simulates human as repeating their last orders', () => {
-    let s = initialState({
+    const s = initialState({
       cast: ['chump', 'carnage', 'player1'],
       difficulty: 'hard',
       seed: 'lookahead-human-with-history',