Add views, import/duplicate, DRC, jumps toggle, multi-wire select, auto-route, delete view tabs

- Roadmap #22: File→Import JSON to restore a diagram (drag-drop or file picker)
- Roadmap #23: Duplicate diagram from diagram list
- Roadmap #24: DRC panel with collapsible categories (unconnected pins, dup refs, no length, no P/N)
- Multi-view tabs: named views per diagram with independent device/wire layouts; snapshot-on-entry prevents bleed
- Keyboard arrow nudge for selected device(s)
- Undo for move, duplicate, label/property changes
- Wire jump arcs toggle (⌒ Jumps button in toolbar)
- Shift+click multi-wire selection; right-click bulk clear waypoints or auto-route
- Auto-route: obstacle-avoiding ortho routing for single or bulk selected wires
- Delete view tab with × button; right-click context menu for rename/delete

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/app/models.py

@@ -16,6 +16,7 @@ class Diagram(Base):
     devices      = relationship("Device",      back_populates="diagram", cascade="all, delete-orphan")
     wires        = relationship("Wire",        back_populates="diagram", cascade="all, delete-orphan")
     wire_bundles = relationship("WireBundle",  back_populates="diagram", cascade="all, delete-orphan")
+    views        = relationship("DiagramView", back_populates="diagram", cascade="all, delete-orphan")
 
 
 class WireBundle(Base):
@@ -89,6 +90,40 @@ class Wire(Base):
     bundle  = relationship("WireBundle", back_populates="wires", foreign_keys=[bundle_id])
 
 
+class DiagramView(Base):
+    __tablename__ = "diagram_views"
+    id         = Column(Integer, primary_key=True, index=True)
+    diagram_id = Column(Integer, ForeignKey("diagrams.id", ondelete="CASCADE"), nullable=False)
+    name       = Column(String, nullable=False, default="View")
+    route_mode = Column(String, default="direct")
+    created_at = Column(DateTime, default=datetime.datetime.utcnow)
+
+    diagram          = relationship("Diagram", back_populates="views")
+    device_positions = relationship("ViewDevicePosition", back_populates="view", cascade="all, delete-orphan")
+    wire_waypoints   = relationship("ViewWireWaypoints",  back_populates="view", cascade="all, delete-orphan")
+
+
+class ViewDevicePosition(Base):
+    __tablename__ = "view_device_positions"
+    id        = Column(Integer, primary_key=True, index=True)
+    view_id   = Column(Integer, ForeignKey("diagram_views.id", ondelete="CASCADE"), nullable=False)
+    device_id = Column(Integer, ForeignKey("devices.id",       ondelete="CASCADE"), nullable=False)
+    x = Column(Float, nullable=False, default=100)
+    y = Column(Float, nullable=False, default=100)
+
+    view = relationship("DiagramView", back_populates="device_positions")
+
+
+class ViewWireWaypoints(Base):
+    __tablename__ = "view_wire_waypoints"
+    id      = Column(Integer, primary_key=True, index=True)
+    view_id = Column(Integer, ForeignKey("diagram_views.id", ondelete="CASCADE"), nullable=False)
+    wire_id = Column(Integer, ForeignKey("wires.id",         ondelete="CASCADE"), nullable=False)
+    waypoints = Column(JSON, default=[])
+
+    view = relationship("DiagramView", back_populates="wire_waypoints")
+
+
 class CustomConnector(Base):
     __tablename__ = "custom_connectors"
     id          = Column(Integer, primary_key=True, index=True)