When Pulse starts before AI is configured, legacyService is nil.
Saving AI settings called Restart() which bailed immediately on the
nil check, leaving the service unstarted (503 on /api/ai/sessions)
until a full process restart.
Merged the nil and !IsRunning checks so first-time configure now
starts the service inline, same as the already-handled stopped case.
Also: bare model names that ParseModelString routes to Ollama (e.g.
"qwen3-omni") now fall back to a configured custom OpenAI base URL
when Ollama is not explicitly configured — handles manually-typed
model names on self-hosted OpenAI-compatible endpoints.
Fixes#1339, #1296
rcourtman
e137f3fbf7