Semantic Todoist Sync 0.8.27

Fix llama-server-backed OpenWebUI chat failures. OpenWebUI may return Responses API SSE events (response.output_text.delta and response.completed) through its OpenAI-compatible route; the plugin now parses that completed envelope while retaining existing Chat Completions SSE and Ollama NDJSON handling. Validated against the live connected model in Obsidian and with 104 local regression assertions.