Threads coordinator_url from CF_ORCH_URL env var (default localhost:7700)
into the cfcore TaskScheduler so Docker instances can point at
host.docker.internal:7700 instead of the container's own loopback.
Also adds CF_ORCH_URL to compose.test-cfcore.yml and mounts persistent
patched configs (llm.docker.yaml, user.docker.yaml) for the test instance.
VRAM detection now uses cf-orch free VRAM when coordinator is running,
making the scheduler cooperative with other cf-orch consumers.
Enqueue return value now checked — queue-full tasks are marked failed.
