feat: Phase 3 core completions — FIM, Agents, Embeddings
Add FIM, Agents, and Embedding endpoints:
- fim/request.go: FIMCompletionRequest (prompt/suffix model)
- agents/request.go: AgentsCompletionRequest (agent_id + messages)
- embedding/embedding.go: Request/Response/Data types with dtype/encoding
- FIMComplete, FIMCompleteStream, AgentsComplete, AgentsCompleteStream,
CreateEmbeddings service methods
- All reuse chat.CompletionResponse/CompletionChunk for responses
- 11 new httptest-based tests
vikingowl
07505b333f