chore(frontend): pin obol-frontend to v0.1.28-rc5

Multi-arch index digest (linux/amd64 + linux/arm64) for the front-end
v0.1.28-rc5 release, which carries the /storefront branding editor that
this RC's live-preview renderer serves.

rc5 rather than rc4 because a second dependency bundle landed on the
front-end main after rc4 was tagged; Docker Hub enforces tag
immutability on that repo, so republishing rc4 was not an option.

Author: bussyjd

internal/embed/infrastructure/values/obol-frontend.yaml.gotmpl

@@ -52,8 +52,8 @@ image:
   pullPolicy: IfNotPresent
   # Digest-pinned: tag is informational, sha256 is authoritative. Eliminates
   # the mutable-tag attack surface called out by the v0.10.0-rc2 supply-chain
-  # review. Multi-arch index digest for v0.1.28-rc3 (linux/amd64 + linux/arm64).
-  tag: "v0.1.28-rc3@sha256:eaf7afc6242b480a873df8bd55d0076641ce5407278813eb9856c19274a15f17"
+  # review. Multi-arch index digest for v0.1.28-rc5 (linux/amd64 + linux/arm64).
+  tag: "v0.1.28-rc5@sha256:e44d9614c7c3ddc657273386abd1e980e47efa6ffa839c57ab5b7840de2198b0"
 
 service:
   type: ClusterIP