concore run: add optional --compose to generate docker-compose.yml for docker studies

[avinxshKD]

Adds a small CLI-only enhancement to concore run for Docker workflows.

--compose now generates docker-compose.yml in the study output directory (one service per node, predictable names, study mounts), so users can run with docker compose up directly.

Scope is intentionally narrow:

works only with --type docker
no backend/mkconcore internals changed
covers single-node and multi-node graphs
includes CLI tests and README update for usage

closes #513

[avinxshKD]

Hey @pradeeban Pls take a look, this adds optional --compose support so Docker studies can start with docker compose up. which should make first-run setup much smoother for users.