Initial commit — wiring diagram maker with full feature set

- FastAPI + SQLite backend with routers for diagrams, devices, wires,
  bundles, connectors, export, and Octopart/Nexar search
- Konva.js canvas: ortho/direct/curved routing, wire crossings, harness
  mode, snap-to-grid, multi-select, drag, resize, undo
- Wire features: color/stripe, twisted pair helix, shielded glow,
  gauge size label, multi-core bundle grouping, length/unit tracking
- Device library: connector, terminal block, cable, splice, label, group,
  relay, fuse, switch, component with custom connector support
- Exports: BOM CSV, assembly TXT, JSON, formboard layout, PNG image
- Auto-migration for schema changes via ALTER TABLE at startup

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

backend/run.py

@@ -0,0 +1,4 @@
+import uvicorn
+
+if __name__ == "__main__":
+    uvicorn.run("app.main:app", host="127.0.0.1", port=8000, reload=False)