Change default PocketBase port to 8070

Set the default listen/host port to 8070 across both the rootless and
root stacks (previously 8080 rootless / 8081 root). Both internal and
external mappings derive from the same PB_PORT/PB_PORT_ROOT variables,
so a single change covers container and host.

Updated .env.example, both Dockerfiles (ENV/EXPOSE), both compose files
(env, port mapping, healthcheck), and both entrypoint fallbacks.

Note: both stacks now default to host port 8070, so they can no longer
run simultaneously without overriding PB_PORT_ROOT.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.env.example

@@ -10,10 +10,10 @@ PB_VERSION=0.39.7
 CONTAINER_NAME=pocketbase
 
 # Port PocketBase listens on (used both inside the container and for the host mapping)
-PB_PORT=8080
+PB_PORT=8070
 
 # Port for the root variant (only used with `docker compose --profile root up`)
-PB_PORT_ROOT=8081
+PB_PORT_ROOT=8070
 
 # ── Superuser bootstrap ───────────────────────────────────────────────
 # On every start the entrypoint checks whether PB_ADMIN_EMAIL already exists: