chore(images): pin service image updates

Replace floating service images with reviewable tags or digests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

edu_master/k8s/playwright.yaml

@@ -17,7 +17,7 @@ spec:
     spec:
       containers:
         - name: playwright
-          image: mcr.microsoft.com/playwright:v1.56.0-jammy
+          image: mcr.microsoft.com/playwright:v1.56.1-jammy
           imagePullPolicy: IfNotPresent
           command:
             - npx