Add test infrastructure for safe dependency updates

.github/workflows/test.yml

@@ -0,0 +1,29 @@
+name: Test
+
+on:
+  pull_request:
+    branches:
+      - main
+  push:
+    branches:
+      - main
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout 🛎️
+        uses: actions/checkout@v3
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v3
+        with:
+          node-version: '18'
+          cache: 'npm'
+
+      - name: Install dependencies 📦
+        run: npm ci --legacy-peer-deps
+
+      - name: Run tests 🧪
+        run: npm test

README.md

@@ -3,3 +3,33 @@
 A browser based hex viewer ✨
 
 <img width="1069" alt="image" src="https://github.com/benfoxall/hex/assets/51385/54e2cb3d-c910-466a-bd94-29ba0cdb8f7a">
+
+## Development
+
+### Running Tests
+
+This project includes tests to help catch regressions when updating dependencies:
+
+```bash
+# Run tests once
+npm test
+
+# Run tests in watch mode
+npm run test:watch
+
+# Run tests with UI
+npm run test:ui
+```
+
+### Building
+
+```bash
+npm run build
+```
+
+### Development Server
+
+```bash
+npm start
+```
+