fix: standardize CI workflow to unified pattern

Reference: riotpiao.com action run 496/707

Unified structure:
- test job: all branches + PRs
- build-push job: main push only, depends on test
- Install Node.js before checkout
- Install docker only in build-push
- Proper secrets and env handling
- Docker login + build + push + prune

.gitea/workflows/ci.yaml

@@ -24,8 +24,11 @@ jobs:
       - name: Go vet
         run: go vet ./...
 
-      - name: Go test
-        run: go test ./...
+      - name: Go test -race
+        run: go test ./... -race
+
+      - name: Static build (smoke)
+        run: CGO_ENABLED=0 go build -trimpath -o gateway ./cmd/gateway
 
   build-push:
     name: Build & Push Image
@@ -36,7 +39,7 @@ jobs:
       - name: Install Node.js and Docker
         run: |
           apt-get update
-          apt-get install -y nodejs docker.io
+          apt-get install -y --no-install-recommends nodejs docker.io git
 
       - name: Checkout code
         uses: actions/checkout@v4