feat(labels): add explicit remote label push command

[TrevorBasinger]

Summary

Add an explicit roar label push flow for mutating current remote labels without changing existing local-first roar label set behavior.

This wires roar to the new GLaaS API PATCH /api/v1/labels/current route and keeps the first client slice tightly scoped:

• local label mutation remains local-only by default
• remote mutation is explicit via roar label push
• only current local user-managed labels are pushed
• reserved/system-managed labels are excluded from remote mutation payloads

What changed

• add roar label push <dag|job|artifact> <target>
• add query-layer request/summary support for label push
• add GLaaS client support for patching current labels
• resolve DAG/job remote targets using register-equivalent canonical session hashes
• patch remote labels with filtered user-managed metadata only
• update fake GLaaS test server with PATCH /api/v1/labels/current
• add focused query and CLI/integration coverage
• document the new explicit push command in the README

Behavior notes

• roar label set is unchanged and remains local-only
• remote mutation uses patch-merge semantics from GLaaS
• first-write remote creation is still not supported; if no remote current labels exist yet, GLaaS returns 404
• DAG/job pushes target the same canonical session hash used by register/publish flows
• artifact pushes target the artifact content hash
• reserved/system labels are not sent to the remote API

Testing

Ran:

• ruff check .
• ruff format --check .
• mypy roar
• pytest tests/application/query/test_label.py tests/unit/test_label_service.py tests/integration/test_label_push_cli_integration.py tests/integration/test_put_cli_integration.py tests/happy_path/test_label_command.py

Also ran:

• pytest -m "not live_glaas and not ebpf"

That broader run passed except for one unrelated environment-specific OSMO wheel/platform failure:

• tests/backends/osmo/test_osmo_smoke.py::test_osmo_basic_workflow_submit_and_complete

[christophergeyer]

Super ! 🚢 it