Add test coverage configuration and update workflows

Configured Jest for test coverage reporting, updated test script in `package.json` to include coverage, and modified GitHub Actions workflow to run tests with coverage. Updated `.gitignore` to exclude coverage reports.

Author: starichkov

.github/workflows/node.js.yml

@@ -28,4 +28,5 @@ jobs:
         cache: 'npm'
     - run: npm ci
     - run: npm run build --if-present
-    - run: npm test
+    - name: Run tests with coverage
+      run: npm run test:coverage

.gitignore

@@ -1,4 +1,5 @@
 .idea/
 node_modules/
+coverage/
 
 *.env

jest.config.js

@@ -5,5 +5,19 @@ export default {
   },
   testEnvironment: 'node',
   testMatch: ['**/__tests__/**/*.js', '**/?(*.)+(spec|test).js'],
+  collectCoverageFrom: [
+    "src/**/*.{js,jsx}",
+    "!src/public/**",
+    "!**/node_modules/**"
+  ],
+  coverageDirectory: "coverage",
+  coverageThreshold: {
+    global: {
+      branches: 17,
+      functions: 16,
+      lines: 10,
+      statements: 10
+    }
+  },
   verbose: true
 };

package.json

@@ -5,6 +5,7 @@
   "type": "module",
   "scripts": {
     "test": "node --experimental-vm-modules node_modules/jest/bin/jest.js",
+    "test:coverage": "node --experimental-vm-modules node_modules/jest/bin/jest.js --coverage",
     "start": "node src/notes-api-server.js"
   },
   "keywords": [],