Add gitea workflow (#78)

Reviewed-on: #78

.gitea/workflows/build.yml

@@ -0,0 +1,24 @@
+name: Backend Build and Test
+on: [push]
+
+jobs:
+  build:
+    runs-on: standard-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Go
+        uses: actions/setup-go@v5
+        with:
+          go-version: '>=1.24'
+
+      - name: Build
+        run: |
+          cd backend
+          go build .
+
+      - name: Test
+        run: |
+          cd backend
+          go test . -v