feat(vision): il server esegue tramite worker e salva misure vere

Aggiunge POST /api/vision/execute: route l'immagine al worker di visione,
mappa le uscite del grafo sulle quote e le salva con save_measurement -
stesso verdetto, stesso gate del fuori tolleranza di ogni altra misura.
Nuova tabella vision_results (una riga per acquisizione, non per quota) e
input_method 'camera' su measurements.

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

src/backend/api/routers/vision.py

@@ -0,0 +1,66 @@
+"""The client asks for a measurement and gets an outcome.
+
+It does not know, and must not know, whether the server or the station computed
+the numbers: that is what lets a station's configuration change without touching
+the frontend or the recipes.
+"""
+from fastapi import APIRouter, Depends, File, Form, HTTPException, UploadFile, status
+from sqlalchemy import select
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from src.backend.api.middleware.api_key import require_measurement_tec
+from src.backend.database import get_db
+from src.backend.models.api.vision import VisionExecuteResponse, VisionMeasurementResult
+from src.backend.models.orm.task import RecipeTask
+from src.backend.models.orm.user import User
+from src.backend.services import vision_service
+
+router = APIRouter(prefix="/api/vision", tags=["vision"])
+
+
+async def _task_or_404(db: AsyncSession, task_id: int) -> RecipeTask:
+    """Shared by the endpoints of this router."""
+    task = (await db.execute(
+        select(RecipeTask).where(RecipeTask.id == task_id)
+    )).scalar_one_or_none()
+    if task is None:
+        raise HTTPException(
+            status_code=status.HTTP_404_NOT_FOUND, detail="Task not found"
+        )
+    return task
+
+
+@router.post("/execute", response_model=VisionExecuteResponse)
+async def execute(
+    task_id: int = Form(...),
+    image: UploadFile = File(...),
+    lot_number: str | None = Form(None),
+    serial_number: str | None = Form(None),
+    production_run_id: int | None = Form(None),
+    db: AsyncSession = Depends(get_db),
+    current_user: User = Depends(require_measurement_tec),
+) -> VisionExecuteResponse:
+    task = await _task_or_404(db, task_id)
+
+    result, saved = await vision_service.execute_task(
+        db,
+        task,
+        await image.read(),
+        current_user.id,
+        version_id=task.version_id,
+        lot_number=lot_number,
+        serial_number=serial_number,
+        production_run_id=production_run_id,
+    )
+    await db.commit()
+
+    return VisionExecuteResponse(
+        vision_result_id=result.id,
+        engine_version=result.engine_version,
+        measurements=[
+            VisionMeasurementResult(
+                subtask_id=m.subtask_id, value=float(m.value), pass_fail=m.pass_fail,
+            )
+            for m in saved
+        ],
+    )