add GitHub Actions workflow for Postgres memory tests

.github/workflows/postgres-memory-tests.yml

@@ -0,0 +1,44 @@
+name: Postgres memory store tests
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  postgres-tests:
+    runs-on: ubuntu-latest
+    services:
+      postgres:
+        image: postgres:15
+        env:
+          POSTGRES_USER: postgres
+          POSTGRES_PASSWORD: postgres
+          POSTGRES_DB: distill_test
+        ports:
+          - 5432:5432
+        options: >-
+          --health-cmd "pg_isready -U postgres -d distill_test"
+          --health-interval 5s --health-timeout 5s --health-retries 5
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Set up Go
+        uses: actions/setup-go@v4
+        with:
+          go-version: '1.24'
+
+      - name: Wait for Postgres
+        run: |
+          for i in {1..10}; do
+            pg_isready -h localhost -p 5432 -U postgres && break || sleep 2
+          done
+
+      - name: Run tests (with Postgres DSN)
+        env:
+          POSTGRES_DSN: postgres://postgres:postgres@localhost:5432/distill_test?sslmode=disable
+        run: |
+          go test -tags=postgres ./... -v