ci: add GitHub Actions test workflow with Codecov coverage

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+name: Tests
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      - run: npm ci
+
+      - name: Run tests with coverage
+        run: npx vitest run --coverage
+
+      - name: Upload coverage to Codecov
+        uses: codecov/codecov-action@v5
+        with:
+          token: ${{ secrets.CODECOV_TOKEN }}
+          files: ./coverage/coverage-final.json
+          fail_ci_if_error: false

README.md

@@ -1,5 +1,8 @@
 # MPNext
 
+[![Tests](https://github.com/MinistryPlatform-Community/MPNext/actions/workflows/test.yml/badge.svg)](https://github.com/MinistryPlatform-Community/MPNext/actions/workflows/test.yml)
+[![codecov](https://codecov.io/gh/MinistryPlatform-Community/MPNext/graph/badge.svg)](https://codecov.io/gh/MinistryPlatform-Community/MPNext)
+
 A modern Next.js application integrated with Ministry Platform authentication and REST API, built with TypeScript, Next.js 16, React 19, and Better Auth.
 
 ## Table of Contents