M0: план разработки, техническая структура, каркас проекта

- docs/PLAN.md — план по этапам, обновляется по мере работы
- docs/TECHNICAL.md — слои, карта папок, контракты, рабочие процессы
- docs/DECISIONS.md — журнал решений, принятых самостоятельно
- разрешение 1080x1920, fit-width (портрет, 4:3..21:9)
- каркас assets/scripts (core / modules / app / ui)
- headless-тесты на vitest + strict typecheck + защита чистоты core
- Rng: детерминированный генератор и перемешивание

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

tests/core/util/Rng.spec.ts

@@ -0,0 +1,62 @@
+import { describe, expect, it } from 'vitest';
+import { Rng } from '@core/util/Rng';
+
+describe('Rng', () => {
+    it('is deterministic for a given seed', () => {
+        const a = Array.from({ length: 20 }, () => new Rng(42).next());
+        expect(new Set(a).size).toBe(1);
+
+        const first = new Rng(7);
+        const second = new Rng(7);
+        for (let i = 0; i < 100; i++) {
+            expect(first.next()).toBe(second.next());
+        }
+    });
+
+    it('produces different streams for different seeds', () => {
+        const a = new Rng(1);
+        const b = new Rng(2);
+        const differs = Array.from({ length: 10 }, () => a.next() !== b.next());
+        expect(differs.some(Boolean)).toBe(true);
+    });
+
+    it('resumes from a captured state', () => {
+        const source = new Rng(123);
+        for (let i = 0; i < 5; i++) source.next();
+
+        const resumed = Rng.fromState(source.state);
+        for (let i = 0; i < 20; i++) {
+            expect(resumed.next()).toBe(source.next());
+        }
+    });
+
+    it('keeps nextInt inside its bound', () => {
+        const rng = new Rng(99);
+        for (let i = 0; i < 10000; i++) {
+            const v = rng.nextInt(36);
+            expect(v).toBeGreaterThanOrEqual(0);
+            expect(v).toBeLessThan(36);
+        }
+    });
+
+    it('rejects a non-positive bound and an empty pick', () => {
+        const rng = new Rng(1);
+        expect(() => rng.nextInt(0)).toThrow(RangeError);
+        expect(() => rng.pick([])).toThrow(RangeError);
+    });
+
+    it('shuffles as a permutation, not a resample', () => {
+        const rng = new Rng(2024);
+        const original = Array.from({ length: 36 }, (_, i) => i);
+        const shuffled = rng.shuffle([...original]);
+
+        expect(shuffled).toHaveLength(36);
+        expect([...shuffled].sort((x, y) => x - y)).toEqual(original);
+        expect(shuffled).not.toEqual(original);
+    });
+
+    it('shuffles reproducibly', () => {
+        const deck = () => Array.from({ length: 36 }, (_, i) => i);
+        expect(new Rng(5).shuffle(deck())).toEqual(new Rng(5).shuffle(deck()));
+    });
+});