test(planning): compare the engine against a frozen engine on random requests

Bundle the planning core at a871f8f (develop after PR #278) as a frozen
fixture and compare it with the current engine on 5,000 seeded random
requests. Outcomes, stable explanations, explanation errors and final-state
snapshots must be strictly deep-equal. Requests cover obligations,
preferences, IF_THEN and TIME_WINDOW rules, earned entitlements, composed
optimization rules, declared days, year boundaries and public holidays.

Refs #280

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

vite.config.mts

@@ -3,6 +3,7 @@
 import angular from '@analogjs/vite-plugin-angular';
 
 import { defineConfig } from 'vite';
+import { coverageConfigDefaults } from 'vitest/config';
 
 // https://vitejs.dev/config/
 export default defineConfig(({ mode }) => {
@@ -18,6 +19,7 @@ export default defineConfig(({ mode }) => {
 			coverage: {
 				provider: 'istanbul',
 				reporter: ['text', 'html', 'cobertura'],
+				exclude: [...coverageConfigDefaults.exclude, '**/frozen-engine/**'],
 			},
 		},
 		define: {