SeaweedFS: S3 gateway on the compose network only

PocketBase reaches the gateway over the compose network (or inside the
AIO container), so publishing 8333 on the host only made a second
SeaweedFS stack fail with "port is already allocated". Drop the binding
and SEAWEED_S3_BIND/SEAWEED_S3_PORT.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

Docker-AIO/.env.seaweedfs.split.example

@@ -93,14 +93,14 @@ SEAWEED_ADMIN_PASSWORD=
 
 # --- SeaweedFS host ports (optional; defaults shown) -------------------------
 # Published for aws-cli, `weed shell` and poking around while developing. The
-# stack itself reaches every one of these over the compose network.
+# stack itself reaches every one of these over the compose network, and the S3
+# gateway too, which is not published so a second stack cannot clash on it.
 # Note SEAWEED_VOLUME_PORT: the volume server serves file content by id with NO
 # authentication, so do not carry this mapping over to a shared machine. It
 # lands on 8081 because API_PORT already has 8080.
 # SEAWEED_MASTER_PORT=9333
 # SEAWEED_VOLUME_PORT=8081
 # SEAWEED_FILER_PORT=8888
-# SEAWEED_S3_PORT=8333
 
 # Existing uploads are NOT migrated when this is switched on: PocketBase copies
 # nothing, so attachments made before the switch stop resolving. Read the file