feat(t103): /health 回 bundle_version（讀 ARCRUN_BUNDLE_VERSION，無 var 回空=老實例）

daemon 比對用（leo：daemon 和雲端是連動的）。vitest 2/2 綠（總管親跑）。
（實作＝子 CC；驗證+commit＝總管）

cypher-executor/tests/health.test.ts

@@ -0,0 +1,27 @@
+import { describe, it, expect } from 'vitest';
+import { SELF } from 'cloudflare:test';
+import { healthRouter } from '../src/routes/health';
+import type { Bindings, ExecutionContext } from '../src/types';
+
+describe('GET /health — bundle_version 欄位', () => {
+  it('無 ARCRUN_BUNDLE_VERSION 時回空字串（老實例情境）', async () => {
+    // wrangler.test.toml 不設此 var → 走 ?? '' fallback
+    const res = await SELF.fetch('http://localhost/health');
+    const data = await res.json() as { ok: boolean; bundle_version: string };
+    expect(res.status).toBe(200);
+    expect(data.ok).toBe(true);
+    expect(data.bundle_version).toBe('');
+  });
+
+  it('有 ARCRUN_BUNDLE_VERSION 時回其值（安裝器注入情境）', async () => {
+    const fakeEnv = { ARCRUN_BUNDLE_VERSION: '2026-07-28/6d06162' } as unknown as Bindings;
+    const res = await healthRouter.fetch(
+      new Request('http://localhost/health'),
+      fakeEnv,
+      {} as ExecutionContext,
+    );
+    const data = await res.json() as { ok: boolean; bundle_version: string };
+    expect(data.ok).toBe(true);
+    expect(data.bundle_version).toBe('2026-07-28/6d06162');
+  });
+});