Add EvoLink model provider

[EvoLinkAI]

Summary

• add an EvoLink model-provider plugin profile using the OpenAI-compatible base URL
• expose EVOLINK_API_KEY / EVOLINK_BASE_URL and EvoLink aliases
• cover profile metadata and alias lookup in provider profile tests

Validation

• uv run --with pytest --with pytest-xdist pytest tests/providers/test_provider_profiles.py => 43 passed
• python3 -m py_compile plugins/model-providers/evolink/init.py
• git diff --check
• rg "evolink/auto|api.evolink.ai|gpt-5.4|gpt-5.5" plugins/model-providers/evolink tests/providers/test_provider_profiles.py => no matches