feat(rack-planner): implement port-to-port connections (patch cables) with dynamic SVG visualization layer

server/routes/connections.ts

@@ -0,0 +1,37 @@
+import { Router } from 'express';
+import * as connService from '../services/connectionService';
+
+const router = Router();
+
+// POST /api/connections
+router.post('/', async (req, res, next) => {
+  try {
+    const { fromPortId, toPortId, color, label } = req.body;
+    const conn = await connService.createConnection({ fromPortId, toPortId, color, label });
+    res.status(201).json(conn);
+  } catch (err) {
+    next(err);
+  }
+});
+
+// DELETE /api/connections/:id
+router.delete('/:id', async (req, res, next) => {
+  try {
+    await connService.deleteConnection(req.params.id);
+    res.json({ success: true });
+  } catch (err) {
+    next(err);
+  }
+});
+
+// DELETE /api/connections/ports/:p1/:p2 (remove link between two specific ports)
+router.delete('/ports/:p1/:p2', async (req, res, next) => {
+  try {
+    await connService.deleteByPorts(req.params.p1, req.params.p2);
+    res.json({ success: true });
+  } catch (err) {
+    next(err);
+  }
+});
+
+export default router;