feat: add build.js script for npm package preparation

- Create scripts/build.js to verify required files before publishing
- Checks for bin/doplan.js, scripts, README.md, and LICENSE
- Validates bin/doplan.js has proper shebang
- Restore build script reference in package.json
- Build script runs before prepublish validation

Author: Test User

package.json

@@ -8,7 +8,8 @@
   },
   "scripts": {
     "postinstall": "node scripts/postinstall.js",
-    "prepublishOnly": "node scripts/prepublish.js"
+    "build": "node scripts/build.js",
+    "prepublishOnly": "npm run build && node scripts/prepublish.js"
   },
   "files": [
     "bin/",

scripts/build.js

@@ -0,0 +1,55 @@
+#!/usr/bin/env node
+
+/**
+ * Build script for npm package
+ * Prepares the package for publishing by verifying required files
+ */
+
+const fs = require('fs');
+const path = require('path');
+
+console.log('DoPlan CLI: Building npm package...');
+
+// Verify required files exist
+const requiredFiles = [
+  'bin/doplan.js',
+  'scripts/postinstall.js',
+  'scripts/prepublish.js',
+  'README.md',
+  'LICENSE'
+];
+
+let hasErrors = false;
+
+for (const file of requiredFiles) {
+  const filePath = path.join(__dirname, '..', file);
+  if (!fs.existsSync(filePath)) {
+    console.error(`Error: Required file missing: ${file}`);
+    hasErrors = true;
+  } else {
+    console.log(`✓ Found: ${file}`);
+  }
+}
+
+// Verify bin/doplan.js is executable (on Unix systems)
+const binPath = path.join(__dirname, '..', 'bin', 'doplan.js');
+if (fs.existsSync(binPath)) {
+  try {
+    // Check if file has shebang
+    const content = fs.readFileSync(binPath, 'utf8');
+    if (!content.startsWith('#!/usr/bin/env node')) {
+      console.warn('Warning: bin/doplan.js missing shebang line');
+    }
+  } catch (error) {
+    console.warn(`Warning: Could not read bin/doplan.js: ${error.message}`);
+  }
+}
+
+if (hasErrors) {
+  console.error('\nBuild failed. Please fix the errors above.');
+  process.exit(1);
+}
+
+console.log('\n✅ Build completed successfully!');
+console.log('Package is ready for publishing.');
+