fix(brew): update Homebrew before non-interactive installs

[ChangeHow]

问题

旧版 Homebrew 不支持 brew install --no-ask，导致选中的软件全部安装失败。

修复

• 检测到 Homebrew 后，首次安装软件前执行一次非交互 brew update
• 更新失败立即终止，避免继续产生部分安装状态
• 更新成功后统一使用最新版支持的 brew install --no-ask
• curl bootstrap、Zsh bootstrap、CLI/App 安装和 benchmark 使用相同语义

验证

• npm test（231 tests passed）
• git diff --check

[github-actions]

Zsh startup benchmark

Ubuntu 24.04 with Linuxbrew, atuin, fnm, fzf, zoxide, zinit, and the shipped plugins. Lower is better.

Warm startup (daily use)

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
current (c9fc0b4)	75.2 ± 0.6	74.6	76.8	1.00
main (4b0e035)	75.9 ± 2.4	74.5	84.9	1.01 ± 0.03
previous commit (4b0e035)	76.1 ± 1.6	74.9	80.9	1.01 ± 0.02

Cache-miss startup

Completion and tool-init caches are removed before every run; installed tools and plugins remain.

Command	Mean [ms]	Min [ms]	Max [ms]	Relative
current (c9fc0b4)	586.4 ± 2.9	583.5	593.1	1.00
main (4b0e035)	586.9 ± 2.6	582.9	590.8	1.00 ± 0.01
previous commit (4b0e035)	592.9 ± 5.9	585.6	603.8	1.01 ± 0.01

[gemini-code-assist]

Code Review

This pull request introduces a mechanism to ensure brew update is run before installing Homebrew packages, while tracking the update state to avoid redundant executions. This logic is implemented across install.sh, src/steps/bootstrap.js, and src/utils/shell.js, with corresponding test updates. The review feedback highlights a potential issue with test isolation and redundant updates due to the module-level global state. It suggests exporting a helper function setHomebrewUpdated to allow resetting the state in tests and updating it in bootstrap.js after the initial update.

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[gemini-code-assist]

为了支持在其他模块和测试中更新或重置 homebrewUpdated 的状态，建议导出一个 setHomebrewUpdated 辅助函数。

这样做有两个主要好处：

1. 避免重复更新：在 src/steps/bootstrap.js 中执行 brew update 后，可以将其设置为 true，从而避免后续调用 brewInstall 时再次触发缓慢的 brew update。
2. 测试隔离：在单元测试中，可以在 beforeEach 中将其重置为 false，防止测试用例之间共享全局状态导致测试不稳定。

let homebrewUpdated = false;

export function setHomebrewUpdated(value) {
  homebrewUpdated = value;
}

[gemini-code-assist]

在成功执行 brew update 并安装 Zsh 后，建议调用 setHomebrewUpdated(true)。

这样可以确保后续通过 brewInstall 安装其他软件时，不会再次触发冗余且缓慢的 brew update，从而显著提升整体安装效率。

注意：

1. 需要在文件顶部导入 setHomebrewUpdated：

   import { commandExists, run, runStream, setHomebrewUpdated } from "../utils/shell.js";

2. 需要在 tests/bootstrap.test.js 的 shell.js 模块 mock 中添加 setHomebrewUpdated: vi.fn()，以避免测试报错。

Suggested change

	if (manager === "brew") {
	await runStream("brew install --no-ask zsh");
	await runStream("env -u HOMEBREW_ASK brew update && brew install --no-ask zsh");
	} else if (manager === "apt-get") {
	if (manager === "brew") {
	await runStream("env -u HOMEBREW_ASK brew update && brew install --no-ask zsh");
	setHomebrewUpdated(true);
	} else if (manager === "apt-get") {

[gemini-code-assist]

由于 homebrewUpdated 是 src/utils/shell.js 中的模块级全局变量，它会在不同的测试用例之间共享。

在当前测试中，第一个 brewInstall("jq") 会将 homebrewUpdated 设为 true。这会导致后续的测试（例如 "propagates Ctrl-C from Homebrew installs"）在调用 brewInstall 时直接跳过 brewUpdate()。

为了保证测试的隔离性，建议在 beforeEach 中重置该状态：

1. 在文件顶部导入 setHomebrewUpdated：

   import { brewInstall, runStream, setHomebrewUpdated } from "../src/utils/shell.js";

2. 在 beforeEach 中重置状态：

   beforeEach(() => {
     vi.clearAllMocks();
     setHomebrewUpdated(false);
   });