feat: add Ollama, Azure OpenAI, and generic OpenAI-compatible providers

[mimran-khan]

Summary

Add three new LLM providers to expand SkillSpector beyond cloud-only OpenAI/Anthropic/NVIDIA endpoints:

• Ollama (SKILLSPECTOR_PROVIDER=ollama) — free local/offline scanning via Ollama's OpenAI-compatible API. No API key required. Supports remote instances via OLLAMA_BASE_URL.
• Azure OpenAI (SKILLSPECTOR_PROVIDER=azure_openai) — enterprise Azure-hosted deployments using AzureChatOpenAI with deployment-based routing, api-version handling, and dedicated env vars (AZURE_OPENAI_ENDPOINT, AZURE_OPENAI_API_KEY, AZURE_OPENAI_DEPLOYMENT).
• Generic OpenAI-compatible (SKILLSPECTOR_PROVIDER=openai_compatible) — Groq, Together AI, Mistral, DeepInfra, Fireworks, and any OpenAI-compatible endpoint via SKILLSPECTOR_COMPAT_API_KEY + SKILLSPECTOR_COMPAT_BASE_URL.

Each provider ships its own model_registry.yaml for accurate token budgeting.

Changes

• src/skillspector/providers/ollama/ — provider, model registry, __init__
• src/skillspector/providers/azure_openai/ — provider, model registry, __init__
• src/skillspector/providers/openai_compatible/ — provider, model registry, __init__
• src/skillspector/providers/__init__.py — register new providers in selector, update error message to mention ollama
• tests/unit/test_new_providers.py — 35 tests covering credentials, chat model creation, metadata, selection, and error messages

Closes #173, closes #174, closes #175

Test plan

• All 35 new tests pass (pytest tests/unit/test_new_providers.py -v)
• All 45 existing provider tests pass (no regressions)
• Ollama always returns credentials (no API key needed)
• Ollama custom base URL via OLLAMA_BASE_URL
• Azure requires both AZURE_OPENAI_API_KEY and AZURE_OPENAI_ENDPOINT
• Azure deployment defaults to model name when AZURE_OPENAI_DEPLOYMENT unset
• Azure API version defaults to 2024-06-01
• Generic requires both SKILLSPECTOR_COMPAT_API_KEY and SKILLSPECTOR_COMPAT_BASE_URL
• All three providers' model registries return correct token budgets
• Unknown provider error message lists all new providers

[rng1995]

[Automated SkillSpector Review]

Approved.

Three providers (Ollama, Azure OpenAI, generic OpenAI-compatible) following the established provider pattern. Credential resolution fails closed (Azure and the generic provider return None unless both env vars are set; Ollama supplies the required placeholder key), the Azure key is wrapped in SecretStr, and each ships a bundled model_registry.yaml. 35 tests cover credentials (positive/negative), chat-model creation, metadata, selection, and the updated error message.

Security: the configurable base URLs (OLLAMA_BASE_URL, SKILLSPECTOR_COMPAT_BASE_URL, AZURE_OPENAI_ENDPOINT) are operator-set env vars — the same trust surface as the existing OPENAI_BASE_URL — so no new attacker-controlled SSRF vector from scanned content. Non-blocking: could validate that the base URL is a well-formed http(s) URL to fail earlier on misconfiguration.