330543f9ce
Adds the vendor-agnostic seam the AI assistant + match-ranking plug into: - LLMProvider / EmbeddingProvider ABCs (base.py). LLM and embeddings are SEPARATE abstractions — Anthropic has no embeddings endpoint, so each is configured independently and either can be off. - NullLLMProvider / NullEmbeddingProvider — the default; fail loud with a clear "not configured" error so AI-off deployments don't silently no-op. - AnthropicLLMProvider — first concrete LLM impl, via the official anthropic SDK (default model claude-opus-4-8). A local provider (e.g. Ollama) would be another subclass of the same interface. - Factory in deps.py (get_llm_provider / get_embedding_provider) selects by env (MODEL_PROVIDER / EMBEDDING_PROVIDER); documented in .env.example. Providers are read-only text/vector producers — they never touch the DB, so the "AI never writes autonomously" invariant (CLAUDE.md #1) holds; writes will go through ChangeProposal (#214). Tests: provider selection (null default, anthropic when keyed, fallback without key) + null providers raise. 81 passed. Closes #215 Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: Justin Paul <justin@jpaul.me>