supamem init ignores QDRANT_API_KEY environment variable (causing 401 Unauthorized)

[raphaelbahat]

Describe the Bug

When running supamem init (with or without --qdrant-url), the Greenfield bootstrap ignores the QDRANT_API_KEY and fallback QDRANT_URL environment variables.

Specifically, inside supamem/init.py, the Qdrant client is instantiated via:

client = _get_client(url)

which defaults to api_key="" (unauthorized). Consequently, if Qdrant requires authentication/API keys, supamem init fails with:

✗ failed to create collection: Unexpected Response: 401 (Unauthorized)
Raw response content:
b'Must provide an API key or an Authorization bearer token'

even if QDRANT_API_KEY is present in the environment.

Additionally, probe_qdrant fails to probe /healthz successfully if the endpoint requires authorization, since it doesn't include the api-key header in the probe request.

To Reproduce

1. Set QDRANT_API_KEY in the environment.
2. Run supamem init --yes --qdrant-url "https://authorized-qdrant-instance.com" --force.
3. See 401 Unauthorized error during collection creation.

Expected Behavior

supamem init should:

1. Fall back to QDRANT_URL environment variable if --qdrant-url is omitted.
2. Respect QDRANT_API_KEY when probing Qdrant and instantiating the Qdrant client during initialization.