feat: add CI test workflow and commands tests (#147)

Testing infrastructure improvements:

1. Add GitHub Actions workflow (.github/workflows/test.yml)
   - Runs on push/PR to main
   - Installs deps, builds, runs tests
   - Blocks merging broken code

2. Add tests for commands.ts (src/core/commands.test.ts)
   - Tests parseCommand() with valid/invalid inputs
   - Tests case insensitivity
   - Tests COMMANDS array and HELP_TEXT

Now at 231 tests across 17 test files.

Written by Cameron ◯ Letta Code

"Test early, test often." - Software proverb

.github/workflows/test.yml

@@ -0,0 +1,27 @@
+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: '20'
+          cache: 'npm'
+      
+      - name: Install dependencies
+        run: npm ci
+      
+      - name: Build
+        run: npm run build
+      
+      - name: Run tests
+        run: npm run test:run