chore(02-01): eslint sim-purity rule + Date.now violator fixture

- eslint.config.js block 3: no-restricted-syntax bans Date.now() and
  setInterval() inside src/sim/**, with src/sim/scheduler/clock.ts as
  the single allowed wall-clock owner (CONTEXT D-33, RESEARCH Pitfall 1)
- date-now-violator.ts deliberate-violation fixture (excluded from
  default lint by Block 1's top-level ignores; the programmatic ESLint
  test passes ignore: false to override)
- lint-firewall.test.ts gains 2 new cases: positive (rule fires on
  violator) + negative (rule does NOT fire on clock.ts the one exception)
- Existing CORE-10 firewall test left untouched and remains green

src/sim/__test_violation__/date-now-violator.ts

@@ -0,0 +1,14 @@
+// DELIBERATE VIOLATION OF CONTEXT D-33 — DO NOT USE OUTSIDE THE FIREWALL TEST.
+//
+// This file lives under src/sim/__test_violation__/ and is excluded from
+// `npm run lint` via the `ignores` block in eslint.config.js. Its sole
+// purpose is to be lint-tested by lint-firewall.test.ts to prove the
+// no-restricted-syntax rule (Phase 2 sim-purity) actually fires.
+//
+// The Vitest test runs ESLint programmatically with `ignore: false`
+// against this file and asserts that `no-restricted-syntax` fires with
+// the D-33 message.
+
+export function violator(): number {
+  return Date.now(); // intentional violation — Phase 2 Plan 02-01 Task 3
+}

src/sim/__test_violation__/lint-firewall.test.ts

@@ -47,3 +47,37 @@ describe('CORE-10: src/sim/ cannot import from src/render/ or src/ui/', () => {
     expect(combined).toMatch(/render|ui/i);
   });
 });
+
+describe('Phase 2 sim-purity rule (CONTEXT D-33)', () => {
+  it('eslint flags Date.now() inside src/sim/** as no-restricted-syntax', async () => {
+    const eslint = new ESLint({
+      overrideConfigFile: resolve(process.cwd(), 'eslint.config.js'),
+      ignore: false,
+    });
+    const fixturePath = resolve(
+      process.cwd(),
+      'src/sim/__test_violation__/date-now-violator.ts',
+    );
+    const results = await eslint.lintFiles([fixturePath]);
+
+    expect(results).toHaveLength(1);
+    const violations = results[0].messages.filter(
+      (m) => m.ruleId === 'no-restricted-syntax',
+    );
+    expect(violations.length).toBeGreaterThanOrEqual(1);
+    expect(violations[0].message).toMatch(/inject time|D-33/);
+  });
+
+  it('does NOT flag Date.now() inside src/sim/scheduler/clock.ts (the one exception)', async () => {
+    const eslint = new ESLint({
+      overrideConfigFile: resolve(process.cwd(), 'eslint.config.js'),
+      ignore: false,
+    });
+    const clockPath = resolve(process.cwd(), 'src/sim/scheduler/clock.ts');
+    const results = await eslint.lintFiles([clockPath]);
+    const noRestrictedViolations = results[0].messages.filter(
+      (m) => m.ruleId === 'no-restricted-syntax',
+    );
+    expect(noRestrictedViolations).toHaveLength(0);
+  });
+});