docs: add Homebrew installation instructions for macOS (#385)

docs/src/app/installation/page.tsx

@@ -10,6 +10,12 @@ export default function Installation() {
         <CodeBlock code={`npm install -g agent-browser
 agent-browser install  # Download Chromium`} />
 
+        <h2>Homebrew (macOS)</h2>
+        <CodeBlock
+          code={`brew install agent-browser
+agent-browser install  # Download Chromium`}
+        />
+
         <h2>From source</h2>
         <CodeBlock code={`git clone https://github.com/vercel-labs/agent-browser
 cd agent-browser

docs/src/app/page.tsx

@@ -9,7 +9,11 @@ export default function Home() {
           Browser automation CLI designed for AI agents. Compact text output minimizes context usage. Fast Rust CLI with Node.js fallback.
         </p>
 
-        <CodeBlock code="npm install -g agent-browser" />
+        <CodeBlock
+          code={`
+npm install -g agent-browser      # all platforms
+brew install agent-browser        # macOS`}
+        />
 
         <h2>Features</h2>
         <ul>