Worker di visione per stazione: modello, API, migrazione 019, execute_task (#45)

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NABedeMX43pyXZbDNUgA5B

src/backend/models/orm/station.py

@@ -25,6 +25,8 @@ class Station(Base):
     location: Mapped[Optional[str]] = mapped_column(String(255), nullable=True)
     notes: Mapped[Optional[str]] = mapped_column(Text, nullable=True)
     active: Mapped[bool] = mapped_column(Boolean, nullable=False, default=True, index=True)
+    # URL del worker di visione della stazione (#45); NULL = worker centrale
+    vision_worker_url: Mapped[Optional[str]] = mapped_column(String(500), nullable=True)
     created_by: Mapped[int] = mapped_column(Integer, ForeignKey("users.id"), nullable=False)
     created_at: Mapped[datetime] = mapped_column(
         DateTime, nullable=False, server_default=func.now()

src/backend/models/orm/vision.py

@@ -26,6 +26,8 @@ class VisionResult(Base):
         Integer, ForeignKey("stations.id"), nullable=True
     )
     device_code: Mapped[Optional[str]] = mapped_column(String(100), nullable=True)
+    # URL del worker effettivamente chiamato (#45), copiato: la stazione puo' cambiarlo dopo
+    worker_url: Mapped[Optional[str]] = mapped_column(String(500), nullable=True)
     # Copied, not referenced: a calibration redone six months from now must not
     # rewrite what a measurement already taken means. Same for the graph.
     calibration_snapshot: Mapped[Optional[dict]] = mapped_column(JSON, nullable=True)