fix(test-harness): restore promisify(exec) + unblock CLI introspection probes

The vitest child-process guard wrapped exec/execFile without preserving the
`[util.promisify.custom]` symbol, so awaited `execAsync` resolved to a raw
stdout string instead of `{stdout, stderr}`. That single regression cascaded
through ~60 "failing" tests across cli, core, engine, and dashboard whose
production code was actually correct. Also relax the AI-CLI blocklist for
cheap introspection (--version/--help/which …), give SIGTERM'd subprocesses a
brief grace period before being flagged as "left running", fix a few real
test-side bugs uncovered along the way (executor mock step transitions, iOS
last-resort keyboard path, mission SSE replay tests racing with the real AI
agent), and convert dashboard route tests' dynamic `await import("../server.js")`
to static imports so first-test timings drop from 2–5s to <200ms.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

packages/dashboard/app/hooks/__tests__/useMobileKeyboard.test.ts

@@ -288,6 +288,9 @@ describe("useMobileKeyboard", () => {
   });
 
   it("treats focused input + viewport shrink as keyboard-open even when overlap is 0", async () => {
+    // iOS last-resort path: chromeOverlap = 0 (innerHeight tracks offsetTop+vv.height),
+    // gap < 16 (focused-fallback doesn't fire), and viewportShrink >= 16 from the
+    // baseline so the focused-input shrink heuristic is the only signal left.
     const { listeners, mockVV } = setupMobileVisualViewport({
       innerHeight: 844,
       vvHeight: 844,
@@ -305,7 +308,17 @@ describe("useMobileKeyboard", () => {
 
     input.focus();
     Object.defineProperty(mockVV, "height", {
-      value: 826,
+      value: 824,
+      writable: true,
+      configurable: true,
+    });
+    Object.defineProperty(mockVV, "offsetTop", {
+      value: 5,
+      writable: true,
+      configurable: true,
+    });
+    Object.defineProperty(window, "innerHeight", {
+      value: 829,
       writable: true,
       configurable: true,
     });
@@ -316,7 +329,7 @@ describe("useMobileKeyboard", () => {
 
     await waitFor(() => {
       expect(result.current.keyboardOverlap).toBe(0);
-      expect(result.current.viewportHeight).toBe(826);
+      expect(result.current.viewportHeight).toBe(824);
       expect(result.current.keyboardOpen).toBe(true);
     });