fix(vision): dichiara le dipendenze del worker, pin numerico HTTP vs runner

Ruling R9: separa l'extra vision (runner: 4 pacchetti VisionSuite + numpy)
da vision-worker (fastapi, uvicorn, pillow, python-multipart, sopra vision).
Prima il worker risolveva solo perche' vs-pm2d le lista per conto suo; un
domani lo stub di stazione dovra' incorporare il runner senza trascinarsi
dietro un server web che non gli serve.

Aggiorna Dockerfile.vision e README.md al nuovo extra; il test del worker ora
pinna anche il valore numerico del diametro (non solo la chiave), agganciato
alla stessa tolleranza del test in-process del runner.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014BBnuACZSCJqXrMYC3LUMU

src/vision_worker/tests/test_worker.py

@@ -16,7 +16,7 @@ pytest.importorskip(
     reason=(
         "the vision tree requires Python >=3.13 (vs-task/vs-measure/vs-pm2d "
         "declare it upstream); run it with "
-        "`uv run --python 3.13 --extra vision --extra dev pytest "
+        "`uv run --python 3.13 --extra vision-worker --extra dev pytest "
         "src/vision_worker/tests`"
     ),
 )
@@ -75,6 +75,12 @@ async def test_run_returns_the_named_outputs():
     body = response.json()
     assert body["failures"] == []
     assert any(key.endswith(".diameter") for key in body["outputs"])
+    # Pinned to src/vision/tests/test_runner.py's in-process expectation
+    # (same graph, same image, same tolerance) - the whole point of a shared
+    # engine_version is that the number does not depend on which path
+    # computed it.
+    diameter = next(v for k, v in body["outputs"].items() if k.endswith(".diameter"))
+    assert diameter == pytest.approx(120.0, abs=4.0)
 
 
 @pytest.mark.asyncio