Add Unity CI/CD workflow for Windows + WebGL builds (closes #59)

.github/workflows/unity-build.yml

@@ -0,0 +1,60 @@
+name: Unity Build (Windows + WebGL)
+
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'unity-client/**'
+  pull_request:
+    branches: [main]
+    paths:
+      - 'unity-client/**'
+  workflow_dispatch:
+
+env:
+  UNITY_PROJECT_PATH: unity-client
+
+jobs:
+  build:
+    name: Build ${{ matrix.targetPlatform }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        targetPlatform:
+          - StandaloneWindows64
+          - WebGL
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          lfs: true
+
+      - name: Cache Unity Library
+        uses: actions/cache@v4
+        with:
+          path: ${{ env.UNITY_PROJECT_PATH }}/Library
+          key: Library-${{ matrix.targetPlatform }}-${{ hashFiles(format('{0}/Assets/**', env.UNITY_PROJECT_PATH)) }}
+          restore-keys: |
+            Library-${{ matrix.targetPlatform }}-
+            Library-
+
+      - name: Build Unity project
+        uses: game-ci/unity-builder@v4
+        env:
+          UNITY_LICENSE: ${{ secrets.UNITY_LICENSE }}
+          UNITY_EMAIL: ${{ secrets.UNITY_EMAIL }}
+          UNITY_PASSWORD: ${{ secrets.UNITY_PASSWORD }}
+        with:
+          projectPath: ${{ env.UNITY_PROJECT_PATH }}
+          targetPlatform: ${{ matrix.targetPlatform }}
+          buildName: CommanderAILab
+          versioning: Semantic
+
+      - name: Upload build artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: Build-${{ matrix.targetPlatform }}
+          path: build/${{ matrix.targetPlatform }}
+          retention-days: 14