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/main.py

@@ -22,6 +22,7 @@ from src.backend.api.routers.statistics import router as statistics_router
 from src.backend.api.routers.setup import router as setup_router
 from src.backend.api.routers.stations import router as stations_router
 from src.backend.api.routers.production import router as production_router
+from src.backend.api.routers.vision import router as vision_router
 
 
 @asynccontextmanager
@@ -75,6 +76,7 @@ app.include_router(reports_router)
 app.include_router(setup_router)
 app.include_router(stations_router)
 app.include_router(production_router)
+app.include_router(vision_router)
 
 
 @app.get("/api/health")