fix(ci): add PostgreSQL service to Docker publish workflow

The Docker Hub Release workflow's test job was missing the PostgreSQL
service required by the test suite. This caused the workflow to fail
before building and pushing the Docker image, resulting in missing
container images (e.g., v0.5.2).

Add the PostgreSQL service configuration matching ci.yml:
- PostgreSQL 16-alpine service container
- Health check configuration
- DATABASE_URL environment variable
- Database initialization step

Fixes #193

.github/workflows/docker-publish.yml

@@ -18,10 +18,32 @@ jobs:
   test:
     name: Pre-publish Tests
     runs-on: ubuntu-latest
+    services:
+      postgres:
+        image: postgres:16-alpine
+        env:
+          POSTGRES_USER: postgres
+          POSTGRES_PASSWORD: postgres
+          POSTGRES_DB: oxicloud_test
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd "pg_isready -U postgres"
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+    env:
+      DATABASE_URL: "postgres://postgres:postgres@localhost/oxicloud_test"
     steps:
       - uses: actions/checkout@v6
       - uses: dtolnay/rust-toolchain@stable
       - uses: Swatinem/rust-cache@v2
+
+      - name: Initialize test database
+        run: psql -h localhost -U postgres -d oxicloud_test -f migrations/20260307000000_initial_schema.sql
+        env:
+          PGPASSWORD: postgres
+
       - run: cargo test --workspace
 
   # Build and push multi-arch image in a single job