fix: update DXT building documentation to use correct npm script names

- Change dxt:build → mcpb:build
- Change dxt:pack → mcpb:pack
- Update test error message for correct script name

Author: drewburchfield

helpscout-mcp-extension/README.md

@@ -17,10 +17,10 @@ From the project root directory:
 
 ```bash
 # Build the DXT extension
-npm run dxt:build
+npm run mcpb:build
 
 # Build and pack the DXT file
-npm run dxt:pack
+npm run mcpb:pack
 ```
 
 This will:
@@ -56,6 +56,6 @@ The build process:
 
 To test locally before publishing:
 ```bash
-npm run dxt:pack
+npm run mcpb:pack
 # Install the generated .dxt file in Claude Desktop
 ```

src/__tests__/dxt-validation.test.ts

@@ -11,7 +11,7 @@ describe('DXT Extension Validation', () => {
   beforeAll(() => {
     // Ensure DXT is built before running tests
     if (!fs.existsSync(buildDir)) {
-      throw new Error('DXT build directory not found. Run `npm run dxt:build` first.');
+      throw new Error('DXT build directory not found. Run `npm run mcpb:build` first.');
     }
 
     if (!fs.existsSync(manifestPath)) {