Docs: OpenAI vision how-to miscounts API requests and its snippet drops `version=`

The OpenAI vision how-to miscounts the example's API requests, and its snippet drops the explicit `version=` that the same page tells you to pass. ## 1. "one model request per episode" is wrong - `docs/how-to/call-openai-vision.md:92-93` says the example "makes one model request per episode". - Reality: `examples/openai_vision/pipeline.py` ships two checks, each making its own `client.responses.create` call (`describe_activity` at line 55, `hand_visibility` at line 98), so an episode makes two requests. The page's own intro says the example ships two checks, and `examples/README.md` says "Each check is one API call". - Fix: say "one model request per check (two per episode)". The `fps=0.5` and `max_tiles=12` numbers in the same sentence are correct; leave them. ## 2. The snippet omits `version=` - The snippet at `docs/how-to/call-openai-vision.md:64` reads `@app.check(uses="vision")`, but the real decorator is `@app.check(uses=OPENAI_ENDPOINT_ALIAS, version="responses-contact-sheet-v1")` (`examples/openai_vision/pipeline.py:42`). The prose right below (lines 94-96) tells the reader to "version the step explicitly when external model configuration cannot be hashed from the function", so the snippet contradicts the page's own advice. - Fix: add the `version=` argument to the snippet. Whether to also switch `uses="vision"` to the alias constant is your call; keeping the snippet minimal is fine as long as `version=` appears. ## Definition of done - The request-count sentence matches the example's actual behavior. - The snippet passes an explicit `version=`. - Line numbers above are from current main; re-check them before editing. ## Validation ```bash lychee --no-progress --include-fragments \ --exclude '^https://github\.com/Hebbian-Robotics/hflow/(issues|security/advisories/new)$' \ --exclude-path references/mcap-spec.md \ --exclude-path references/foxglove-CompressedVideo.proto . ```