feat(no-release): Add AGENTS.md file

mentioned in commit 9a903e95

mentioned in merge request gitlab-org/cli!2449 (merged)

mentioned in merge request gitlab-com/gl-infra/woodhouse!681

mentioned in merge request gitlab-org/terraform-provider-gitlab!2727 (merged)

mentioned in merge request gitlab-org/release-tools!4516 (merged)

mentioned in merge request gitlab-com/gl-infra/oncall-robot-assistant!104

mentioned in merge request gitlab-org/terraform-provider-gitlab!2728 (closed)

mentioned in merge request fforster/epic-update!25 (merged)

mentioned in merge request fforster/gitlab-mcp!179 (merged)

mentioned in merge request schober-server/kubernetes/images/gitlab-token-refresher!35

mentioned in merge request gitlab-com/gl-infra/autolabels!108 (merged)

mentioned in merge request gitlab-com/gl-infra/platform/runway/runwayctl!1267 (merged)

mentioned in merge request gitlab-com/gl-infra/ringctl!371

mentioned in merge request sickit/token-operator!17

mentioned in merge request gitlab-org/container-registry!2558 (merged)