Add HTTP server mode with native node:http

Reintroduce server mode (removed in 3014cf9) using node:http instead of
Express — zero new dependencies. Accepts JSON commands via POST to /,
returns JSON responses with CORS support. Screenshot command returns
base64 data when no path is specified.

- Add src/server.ts with BrowserServer class using node:http
- Add -s/--server <port> CLI flag (default 13373)
- Export BrowserServer and startServer from index.ts

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dist/cli.js

@@ -5,6 +5,7 @@ import { fileURLToPath } from 'node:url';
 import { parseArgs } from 'node:util';
 import { ClaudeBrowser } from './browser.js';
 import * as image from './image.js';
+import { startServer } from './server.js';
 const __dirname = dirname(fileURLToPath(import.meta.url));
 const pkg = JSON.parse(readFileSync(resolve(__dirname, '../package.json'), 'utf-8'));
 const { values, positionals } = parseArgs({
@@ -24,6 +25,7 @@ const { values, positionals } = parseArgs({
         json: { type: 'boolean', short: 'j', default: false },
         click: { type: 'string', short: 'c', multiple: true },
         type: { type: 'string', short: 't', multiple: true },
+        server: { type: 'string', short: 's' },
         help: { type: 'boolean', default: false },
         version: { type: 'boolean', short: 'v', default: false },
         // Image processing options
@@ -51,6 +53,7 @@ Options:
   -j, --json              Output query results as JSON
   -c, --click <selector>  Click on element (can be repeated for multiple clicks)
   -t, --type <sel>=<text> Type text into input (can be repeated)
+  -s, --server <port>     Start HTTP server mode (default port: 13373)
   -v, --version           Show version
   --help                  Show this help
 
@@ -78,6 +81,10 @@ Image processing examples:
   browse https://example.com --resize 800x600
   browse https://example.com --compress 60
 
+Server mode:
+  browse -s 13373                           # Start HTTP server on port 13373
+  curl localhost:13373 -d '{"cmd":"goto","url":"https://example.com"}'
+
 MCP Server (for Claude Code integration):
   browse-mcp                        # Run as MCP server (stdio transport)
 `;
@@ -219,6 +226,11 @@ async function main() {
         console.log(HELP);
         process.exit(0);
     }
+    if (values.server !== undefined) {
+        const port = Number.parseInt(values.server) || 13373;
+        await startServer({ port });
+        return;
+    }
     if (positionals.length === 0) {
         console.log(HELP);
         process.exit(0);