test(ui): flush passive effects with React act in CompanySkills tests (#12878)

## Thinking Path

> - Paperclip is the open source app people use to manage AI agents for
work.
> - The user interface tests verify company skill installation flows.
> - The install-preview dialog sets state through passive React effects.
> - The local test helper flushed render work but did not flush passive
effects.
> - Timer hops did not guarantee that React completed those effects
before user actions.
> - This pull request delegates the helper to React act and removes the
timer hops.
> - The benefit is deterministic CompanySkills tests without a
product-code change.

## Linked Issues or Issue Description

**What happened?**

The CompanySkills install-preview dialog tests used a timer hop after
opening the dialog. The timer could run before React completed passive
effects. A later click then used stale dialog state.

**Expected behavior**

The test helper must flush passive effects before the test interacts
with the dialog. The tests must pass without a race between timer
callbacks and React scheduler tasks.

**Steps to reproduce**

1. Run the CompanySkills test file many times from the ui directory.
2. Observe intermittent failures that report an empty agent list or a
null slug.
3. Run the same tests with React act to flush passive effects.

**Paperclip version or commit**

Commit 834f33c31b.

**Deployment mode**

Local dev (pnpm dev).

**Installation method**

Built from source (pnpm dev / pnpm build).

**Agent adapter(s) involved**

Not adapter-specific (core bug).

**Database mode**

Not database-related.

## What Changed

- Delegate the local test helper to React act.
- Remove four setTimeout(0) hops that no longer provide synchronization.
- Keep all 29 tests and all product code unchanged.

## Verification

- Run npx vitest run src/pages/CompanySkills.test.tsx from ui/.
- Run pnpm --filter @paperclipai/ui exec tsc --noEmit.
- Confirm that the full CI suite passes.

## Risks

Low risk. The change affects one test helper and one test file. It
changes test synchronization only.

## Model Used

OpenAI Codex, GPT-5, with tool use and code review support. The exact
context window and reasoning configuration are not exposed in this run.

## Checklist

- [x] I have included a thinking path that traces from project context
to this change
- [x] I have specified the model used (with version and capability
details)
- [x] I have checked ROADMAP.md and confirmed this PR does not duplicate
planned core work
- [x] I have searched GitHub for duplicate or related PRs and linked
them above
- [x] I have either (a) linked existing issues with Fixes: # / Closes #
/ Refs # OR (b) described the issue in-PR following the relevant issue
template
- [x] I have not referenced internal/instance-local Paperclip issues or
links (only public GitHub #NNN / github.com/paperclipai/paperclip URLs)
- [x] My branch name describes the change (for example test/...) and
contains no internal Paperclip ticket id or instance-derived details
- [x] I have run tests locally and they pass
- [x] I have added or updated tests where applicable
- [x] I have updated relevant documentation to reflect my changes
- [x] I have considered and documented any risks above
- [x] All Paperclip CI gates are green
- [x] Greptile is 5/5 with no open P2s, recommendations, or follow-ups
- [x] I will address all Greptile and reviewer comments before
requesting merge


Co-authored-by: Paperclip <noreply@paperclip.ing>

ui/src/pages/CompanySkills.test.tsx

@@ -1,7 +1,6 @@
 // @vitest-environment jsdom
 
-import type { ComponentProps, ReactNode } from "react";
-import { flushSync } from "react-dom";
+import { act as reactAct, type ComponentProps, type ReactNode } from "react";
 import { createRoot, type Root } from "react-dom/client";
 import type { CatalogSkill, CompanySkillDetail, CompanySkillListItem, CompanySkillVersion, FolderListResult } from "@paperclipai/shared";
 import { afterEach, describe, expect, it, vi } from "vitest";
@@ -104,11 +103,9 @@ let root: Root | null = null;
 let container: HTMLDivElement | null = null;
 
 async function act(callback: () => void | Promise<void>) {
-  let result: void | Promise<void> = undefined;
-  flushSync(() => {
-    result = callback();
+  await reactAct(async () => {
+    await callback();
   });
-  await result;
 }
 
 afterEach(() => {
@@ -1043,11 +1040,6 @@ describe("install-time agent enablement", () => {
         />,
       );
     });
-    // The dialog seeds its slug/agent state in passive effects; give them a
-    // macrotask to flush before interacting.
-    await act(async () => {
-      await new Promise((resolve) => setTimeout(resolve, 0));
-    });
 
     const node = container as ParentNode;
     expect(node.textContent).toContain("Enable for agents");
@@ -1089,15 +1081,9 @@ describe("install-time agent enablement", () => {
 
     // Dialog opens before the agents query resolves: nothing to select yet.
     await act(async () => renderDialog([]));
-    await act(async () => {
-      await new Promise((resolve) => setTimeout(resolve, 0));
-    });
 
     // The agents arrive later; the untouched selection must pick them up.
     await act(async () => renderDialog(agentOptions));
-    await act(async () => {
-      await new Promise((resolve) => setTimeout(resolve, 0));
-    });
 
     await click(buttonsNamed(container as ParentNode, "Install skill")[0] as HTMLButtonElement);
 
@@ -1129,9 +1115,6 @@ describe("install-time agent enablement", () => {
         />,
       );
     });
-    await act(async () => {
-      await new Promise((resolve) => setTimeout(resolve, 0));
-    });
 
     const node = container as ParentNode;
     expect(node.textContent).not.toContain("Enable for agents");