Provider setup docs omit supported backends #433

Problem

The setup surfaces users follow before their first scan do not match the current provider selector:

• .env.example lists only openai, anthropic, anthropic_proxy, and nv_build.
• docs/DEVELOPMENT.md lists only a subset of providers and credentials.
• The README provider table and environment-variable table omit the dedicated ollama, azure_openai, and openai_compatible backends and do not fully describe gemini_cli.

All four backends are accepted by SKILLSPECTOR_PROVIDER on current main. Users copying the template or following the setup guide can therefore configure an indirect workaround or conclude the backend is unsupported.

Expected behavior

The checked-in environment template and setup documentation should list the usable provider names and the matching credentials, endpoints, or local-auth behavior from the current provider implementations.