feat: Add GitHub deployment artifacts (homebrew, npm) (gt-ufep6)

- Add .goreleaser.yml for multi-platform binary releases
- Add npm-package/ with postinstall binary download
- Add release.yml workflow for GoReleaser + npm publish + Homebrew tap

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

npm-package/bin/gt.js

@@ -0,0 +1,54 @@
+#!/usr/bin/env node
+
+const { spawn } = require('child_process');
+const path = require('path');
+const os = require('os');
+const fs = require('fs');
+
+// Determine the platform-specific binary name
+function getBinaryPath() {
+  const platform = os.platform();
+  const arch = os.arch();
+
+  let binaryName = 'gt';
+  if (platform === 'win32') {
+    binaryName = 'gt.exe';
+  }
+
+  // Binary is stored in the package's bin directory
+  const binaryPath = path.join(__dirname, binaryName);
+
+  if (!fs.existsSync(binaryPath)) {
+    console.error(`Error: gt binary not found at ${binaryPath}`);
+    console.error('This may indicate that the postinstall script failed to download the binary.');
+    console.error(`Platform: ${platform}, Architecture: ${arch}`);
+    process.exit(1);
+  }
+
+  return binaryPath;
+}
+
+// Execute the native binary with all arguments passed through
+function main() {
+  const binaryPath = getBinaryPath();
+
+  // Spawn the native gt binary with all command-line arguments
+  const child = spawn(binaryPath, process.argv.slice(2), {
+    stdio: 'inherit',
+    env: process.env
+  });
+
+  child.on('error', (err) => {
+    console.error(`Error executing gt binary: ${err.message}`);
+    process.exit(1);
+  });
+
+  child.on('exit', (code, signal) => {
+    if (signal) {
+      process.exit(1);
+    }
+    process.exit(code || 0);
+  });
+}
+
+main();