Fix image tags that failed to pull on test-cloud

- discourse: 2026.10.0 -> 2026.10.0-latest (correct tag format)
- formbricks: Docker Hub 6.1.0 -> ghcr.io 4.6.0 (moved to GHCR)
- zulip: Docker Hub 12.3-0 -> ghcr.io 12.3-0 (12.x on GHCR)
- open-webui: v0.12.3 -> v0.12.4 (newer release)

open-webui/versions/0/deployment.yaml

@@ -19,7 +19,7 @@ spec:
           type: RuntimeDefault
       containers:
       - name: open-webui
-        image: ghcr.io/open-webui/open-webui:v0.12.3
+        image: ghcr.io/open-webui/open-webui:v0.12.4
         imagePullPolicy: IfNotPresent
         securityContext:
           allowPrivilegeEscalation: false

open-webui/versions/0/manifest.yaml

@@ -1,4 +1,4 @@
-version: 0.12.3
+version: 0.12.4
 defaultConfig:
   namespace: open-webui
   storage: 2Gi