Camera di stazione: acquisizione dal frontend e campi admin (#72)

Route POST /measure/api/vision/grab (proxy verso il servizio camera),
get_station_by_code, pulsante «Acquisisci dalla camera», grab() in
vision_execute.js, campi camera_url e camera_source nell'admin stazioni,
traduzioni it/en, extra_hosts host.docker.internal nel compose di sviluppo.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/frontend/flask_app/blueprints/measure.py

@@ -345,6 +345,7 @@ def task_execute(task_id: int):
         all_task_ids=all_task_ids,
         measurement_interval_minutes=measurement_interval_minutes,
         allow_manual_input=allow_manual_input,
+        camera_enabled=_station_camera(_current_station()[0]) is not None,
     )
 
 
@@ -1000,6 +1001,64 @@ def api_vision_execute():
     return jsonify(resp), 200
 
 
+def _station_camera(station_code: str | None) -> tuple[str, str] | None:
+    """(camera_url, camera_source) of the station, None when it has no camera.
+
+    A station that cannot be read counts as "no camera": the grab button simply
+    does not show, the file input keeps working.
+    """
+    if not station_code:
+        return None
+    station = api_client.get_station_by_code(station_code)
+    if not isinstance(station, dict) or station.get("error"):
+        return None
+    url = station.get("camera_url")
+    source = station.get("camera_source")
+    if not url or not source:
+        return None
+    return str(url), str(source)
+
+
+# #72: the browser asks the station's camera service (vs-gui) for a frame; the
+# service address is a server-side matter, so Flask relays and the PNG goes back as is.
+@measure_bp.route("/api/vision/grab", methods=["POST"])
+@login_required
+@role_required("MeasurementTec")
+def api_vision_grab():
+    """Proxy: grab one frame from the current station's camera, answer a PNG."""
+    camera = _station_camera(_current_station()[0])
+    if camera is None:
+        return jsonify({
+            "error": True,
+            "detail": _("Camera non configurata per questa stazione"),
+        }), 409
+    camera_url, camera_source = camera
+    try:
+        resp = http_requests.post(
+            f"{camera_url.rstrip('/')}/camera/grab",
+            json={"source": camera_source, "trigger": "continuo", "timeout_ms": 5000},
+            timeout=15,
+        )
+    except http_requests.RequestException as exc:
+        return jsonify({
+            "error": True,
+            "detail": _("Servizio camera non raggiungibile: %(detail)s", detail=str(exc)),
+        }), 502
+    if resp.status_code != 200:
+        detail = ""
+        try:
+            body = resp.json()
+            detail = body.get("detail", "") if isinstance(body, dict) else ""
+        except ValueError:
+            detail = (resp.text or "")[:200]
+        return jsonify({
+            "error": True,
+            "detail": _("Acquisizione non riuscita (%(status)s): %(detail)s",
+                        status=resp.status_code, detail=detail),
+        }), 502
+    return Response(resp.content, content_type="image/png")
+
+
 @measure_bp.route("/api/vision/results/<int:result_id>/image", methods=["GET"])
 @login_required
 @role_required("MeasurementTec")