What

Adds unit tests for the Ollama embedding client and wires all CLI commands through the embedding provider registry instead of hardcoding OpenAI.

Why

The Ollama client (pkg/embedding/ollama) shipped without tests. The CLI commands (api, serve, memory) only accepted OpenAI, even though the registry already supported Ollama and Cohere.

Changes

• 15 unit tests for the Ollama client covering success, errors, empty input, timeouts, batch, and connection failures
• --embedding-provider flag added to api, serve, and memory commands (accepts openai, ollama, cohere)
• --embedding-base-url flag for custom endpoints (e.g. http://localhost:11434 for Ollama)
• Config validation updated to accept ollama and cohere as valid providers
• EmbeddingConfig.BaseURL field added for config file support

Usage

# Use Ollama for embeddings (no API key needed)
distill api --embedding-provider ollama --embedding-model nomic-embed-text

# Use Cohere
distill api --embedding-provider cohere --openai-key $COHERE_API_KEY

# Config file
embedding:
  provider: ollama
  model: nomic-embed-text
  base_url: http://localhost:11434

Closes #25