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/main.py

@@ -7,7 +7,7 @@ from fastapi.staticfiles import StaticFiles
 from sqlalchemy import text, inspect as sa_inspect
 
 from .database import Base, engine, SessionLocal
-from .routers import bundles, connectors, diagrams, devices, export, octopart, wires
+from .routers import bundles, connectors, diagrams, devices, export, octopart, views, wires
 
 Base.metadata.create_all(bind=engine)
 
@@ -45,6 +45,9 @@ def _migrate():
             if "show_size_label" not in _cols("wires"):
                 conn.execute(text("ALTER TABLE wires ADD COLUMN show_size_label INTEGER DEFAULT 0"))
                 conn.commit()
+
+            # diagram_views / view_device_positions / view_wire_waypoints are created
+            # via Base.metadata.create_all — no ALTER TABLE needed for new tables
     except Exception as e:
         print(f"[migrate] column error: {e}", file=sys.stderr)
 
@@ -59,12 +62,13 @@ app.add_middleware(
     allow_headers=["*"],
 )
 
-app.include_router(bundles.router,  prefix="/api/bundles")
-app.include_router(diagrams.router, prefix="/api/diagrams")
-app.include_router(devices.router,  prefix="/api/devices")
-app.include_router(wires.router,    prefix="/api/wires")
-app.include_router(octopart.router, prefix="/api/octopart")
-app.include_router(export.router,   prefix="/api/export")
+app.include_router(bundles.router,   prefix="/api/bundles")
+app.include_router(diagrams.router,  prefix="/api/diagrams")
+app.include_router(devices.router,   prefix="/api/devices")
+app.include_router(wires.router,     prefix="/api/wires")
+app.include_router(views.router,     prefix="/api/views")
+app.include_router(octopart.router,  prefix="/api/octopart")
+app.include_router(export.router,    prefix="/api/export")
 app.include_router(connectors.router, prefix="/api/connectors")
 
 FRONTEND_DIR = os.path.normpath(