Ingesting documents with a local OpenAI-compatible embedding engine (Ollama,
vLLM, ...) failed with `openai.OpenAIError: Missing credentials` when no API
key was configured. The OpenAI-like embedding factory forwarded an empty
api_key straight to the OpenAI client, which rejects empty credentials at
request time.
Chat already tolerates a missing key (completions/openailike.py uses
`... or "default"`) and so does the embedding discovery probe
(`... or "no-key"`); only the embedding factory lacked the fallback, so model
discovery and chat worked while the first real embedding call (ingestion)
crashed.
Mirror the chat behaviour with a placeholder key on the local
OpenAI-compatible path. The strict api.openai.com path is unchanged and still
requires a real key.
Fixes#2260
Co-authored-by: Julian Siegrist <jsiegrist@immomio.de>
