feat(providers): add Eden AI as an OpenAI-compatible provider

[MVS-source]

Summary

Adds Eden AI as an OpenAI-compatible provider. Eden AI is an EU-based unified API to 100+ models (Mistral, OpenAI, Anthropic, Google, …) behind a single OpenAI-compatible endpoint and one key. Per sia/providers.py ("Adding a provider is dropping a JSON file — no code change"), this is a JSON drop-in.

Type of change

• Bug fix
• New feature
• Documentation
• New or updated task
• Evaluation change
• Provider/model configuration
• Security-sensitive change
• Refactor / maintenance
• Other

Related issue

N/A (small, clearly-scoped provider addition)

What changed

• add sia/defaults/providers/edenai.json (client_kind = openai, base_url = https://api.edenai.run/v3, api_key_env = EDENAI_API_KEY)
• cover it in tests/test_providers.py (bundled set + test_load_edenai_provider)
• document it in docs/configuration.md (bundled providers list + EDENAI_API_KEY in the API keys section)

How I tested this

pip install -e ".[dev]"
python -m pytest tests/ -v      # 130 passed, 1 skipped
ruff check sia/ tests/          # passed
ruff format --check sia/ tests/ # passed

Also verified end-to-end against the live Eden AI API: SIA loads the edenai provider and an OpenAI-SDK client at base_url returns valid completions for mistral/mistral-small-latest and openai/gpt-4o-mini.

Security and privacy checklist

• This change does not log API keys, secrets, private task data, or generated credentials.
• This change does not weaken sandboxing, subprocess isolation, or task data boundaries.

The provider file stores only the name of the environment variable (EDENAI_API_KEY), never a key value; the key is read from the environment at runtime, consistent with the other bundled providers.