test(benchmark): keep the a871f8f engine as a fixed calibration engine

The differential check's frozen bundle will be rebuilt for #302; the
relative gate keeps timing the unchanged a871f8f bundle so its ratios
stay comparable with the recorded history.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/app/benchmark/leave-planner-benchmark.spec.ts

@@ -1,5 +1,5 @@
 import { vi } from '../../testing/vitest-compat';
-import { calculatePlanningAsyncInternal } from '../services/frozen-engine/leave-planner.core.frozen.mjs';
+import { calculatePlanningAsyncInternal } from '../services/frozen-engine/leave-planner.core.calibration.mjs';
 import { createPlanningCalculation } from '../services/leave-planner.service';
 import {
 	BENCHMARK_BUDGET_MULTIPLIERS,
@@ -69,7 +69,7 @@ describe('leave planner benchmark protocol', () => {
 					),
 				).toHaveLength(2);
 			}
-			// Frozen engine (a871f8f) on 'two years', best of three: the runner-speed yardstick.
+			// Calibration engine (frozen at a871f8f) on 'two years', best of three: the runner-speed yardstick.
 			const calibrationRequest = scenarios.find((item) => item.name === 'two years')!.request;
 			let calibrationMs = Infinity;
 			for (let run = 0; run < 3; run++) {