DEVX-30: fix: use DOCKER_HOST env var in is_docker_ready + scan all rootless sockets

src/devx/molecule/molecule_ci_guard.py

@@ -321,6 +321,17 @@ def cli(pairs: tuple[str, ...], junit_output: str | None, roles_root: Path | Non
 
             click.echo(_("PASSED: {pair}", pair=pair))
 
+            # Prune Docker data between scenarios to prevent disk exhaustion
+            # in Docker-in-Docker molecule containers (each scenario pulls
+            # hundreds of MB of images that accumulate across pairs).
+            with contextlib.suppress(subprocess.SubprocessError, OSError):
+                subprocess.run(  # nosec B603, B607
+                    ["docker", "system", "prune", "-af", "--volumes"],
+                    check=False,
+                    capture_output=True,
+                    timeout=60,
+                )
+
         click.echo(_("All molecule tests passed."))
         if junit_output:
             write_junit_report(junit_output, testcases, current_index)