fix(backup,restore): make restore drills replayable and leave swarm tasks alone

Restore fixes, both hit by the infinito svc-bkp e2e drill:

- mariadb --empty dropped tables one docker exec at a time with SET
  FOREIGN_KEY_CHECKS=0 issued in a separate client session, so the
  session-scoped toggle never applied and any FK-referenced parent table
  (mailu.users) died with ERROR 1451. Issue the toggle and all DROPs in
  one session.
- postgres --empty now drops only current_user-owned objects (extension
  members like pg_trgm's set_limit are superuser-owned) with IF EXISTS
  absorbing CASCADE fallout, and the replay skips superuser-only dump
  lines (COMMENT ON EXTENSION, ALTER DEFAULT PRIVILEGES) that abort an
  app-user psql run under ON_ERROR_STOP.

Backup fixes:

- pg_dump now runs with --no-owner --no-privileges so future dumps are
  replayable by the owning app user in the first place.
- Swarm task containers are never stopped or started manually: the
  orchestrator replaces a stopped task and a later docker start fails on
  the detached overlay network. filter_stoppable skips them visibly and
  the whitelist stop check ignores them.

Validated end to end against a live infinito compose stack: the full
svc-bkp-volume-2-local drill (verify, restore cycle, sql replay for
mailu, keycloak and one more db) passes with these patches applied.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/baudolo/backup/docker.py

@@ -24,6 +24,31 @@ def containers_using_volume(volume_name: str) -> list[str]:
     )
 
 
+def is_swarm_task(container: str) -> bool:
+    """Swarm-managed task containers must never be stopped or started
+    manually: the orchestrator replaces the stopped task and a later
+    `docker start` fails on the detached overlay network."""
+    out = execute_shell_command(
+        "docker inspect --format "
+        f"'{{{{index .Config.Labels \"com.docker.swarm.task.id\"}}}}' {container}"
+    )
+    return bool(out and out[0].strip())
+
+
+def filter_stoppable(containers: list[str]) -> list[str]:
+    """Containers baudolo may stop/start itself (everything but swarm tasks)."""
+    stoppable = []
+    for container in containers:
+        if is_swarm_task(container):
+            print(
+                f"Skipping stop/start for swarm task container '{container}'.",
+                flush=True,
+            )
+            continue
+        stoppable.append(container)
+    return stoppable
+
+
 def change_containers_status(containers: list[str], status: str) -> None:
     """Stop or start a list of containers."""
     if not containers: