chore(infra): drop aspirational Renovate comments from compose

The repo's renovate.json only configures TipTap grouping; Renovate is
not currently active against MinIO / mc / mailpit / Postgres / Node /
Caddy. The "Renovate keeps it current" comments were aspirational —
those tags will rot until Renovate is bootstrapped (tracked in a
follow-up issue).

The "Pinned mc release; Renovate keeps it current" comment is gone
already since the create-buckets entrypoint was extracted to a script
in the preceding MinIO-policy commit.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

docker-compose.prod.yml

@@ -56,7 +56,8 @@ services:
       retries: 5
 
   minio:
-    # Pinned MinIO release for reproducible deploys; Renovate keeps it current.
+    # Pinned MinIO release for reproducible deploys. Bumped manually until
+    # Renovate is bootstrapped for these production images (see follow-up issue).
     image: minio/minio:RELEASE.2025-02-28T09-55-16Z
     restart: unless-stopped
     command: server /data --console-address ":9001"
@@ -95,7 +96,7 @@ services:
   # Dev-only mail catcher; gated behind the staging profile so production
   # never starts it. Staging workflow runs with `--profile staging`.
   mailpit:
-    # Pinned for reproducibility; Renovate bumps the tag.
+    # Pinned for reproducibility; bumped manually until Renovate is bootstrapped.
     image: axllent/mailpit:v1.29.7
     restart: unless-stopped
     profiles: ["staging"]