fix(gateway): detect Docker/Podman containers for /restart service path

[zccyman]

Summary

The /restart gateway command only detected systemd (INVOCATION_ID) when choosing between the detached-subprocess and service-restart approaches. In Docker/Podman containers, the detached subprocess approach fails because the container stops when PID 1 exits, killing the helper before it can restart anything.

Problem

In a Docker container (e.g. nousresearch/hermes-agent:latest on Unraid):

1. User sends /restart
2. Gateway exits to spawn a detached restart helper
3. tini (PID 1) exits because the gateway exited
4. Docker stops the container
5. The detached helper is killed before it can restart anything
6. Gateway stays dead until manually restarted

Fix

Detect Docker (/.dockerenv) and Podman (/run/.containerenv) alongside systemd. In container environments, use the service restart path (exit code 75) instead of the detached subprocess approach. Combined with a restart policy (unless-stopped or on-failure), Docker/Podman handles the restart correctly.

_under_service = bool(
    os.environ.get("INVOCATION_ID")       # systemd
    or os.path.isfile("/.dockerenv")       # Docker
    or os.path.isfile("/run/.containerenv") # Podman
)

Testing

• All 132 gateway restart-related tests pass

Files Changed

File	Change
gateway/run.py	Added Docker/Podman detection to _under_service check

Closes #25217

[alt-glitch]

Duplicate of #25219 — same fix (Docker/Podman container detection for /restart service path) targeting the same file gateway/run.py and closing the same issue #25217. Also competes with #25263.

[zccyman]

Thanks @alt-glitch for the catch. Closing as duplicate of #25219 — same Docker/Podman detection fix for the same file and issue #25217. Also competing with #25263. 🙏