Update wiring diagram maker: formboard router + frontend

Backend formboard router and frontend (canvas, formboard, connector library,
app/api, index/css) updates. Ignore *.log.

frontend/js/canvas.js

@@ -1188,6 +1188,28 @@ class DiagramCanvas {
         x: 4, y: device.height - 14, width: device.width - 8, align: "right",
         text: "cable", fontSize: 8, fontFamily: "monospace", fill: "#888888",
       }));
+    } else if (device.device_type === "connector" && device.properties?.shape === "circular") {
+      rect.visible(false);
+      // Body radius is intentionally smaller than pin radius (0.471) so wire
+      // endpoints sit outside the body and remain visible above it.
+      const r = Math.min(device.width, device.height) * 0.386;
+      const cx = device.width / 2, cy = device.height / 2;
+      group.add(new Konva.Circle({
+        name: "device-body",
+        x: cx, y: cy, radius: r,
+        fill: this._deviceFill("connector"), stroke: "#5a5a8a", strokeWidth: 2,
+      }));
+      // Key notch anchored to body top edge
+      group.add(new Konva.Rect({
+        x: cx - 5, y: cy - r - 3, width: 10, height: 7, cornerRadius: 2,
+        fill: "#333355", stroke: "#5a5a8a", strokeWidth: 1, listening: false,
+      }));
+      group.add(new Konva.Text({
+        name: "device-label",
+        x: 4, y: cy - 6, width: device.width - 8,
+        text: device.label, fontSize: Math.min(10, fontSize),
+        fontFamily: "monospace", fill: "#dde0f5", align: "center",
+      }));
     } else {
       if (device.reference) {
         group.add(new Konva.Text({ x: 6, y: 5, text: device.reference, fontSize: 10, fontFamily: "monospace", fill: "#99aaee", fontStyle: "bold" }));
@@ -1263,6 +1285,12 @@ class DiagramCanvas {
         this.selectDevice(device.id);
       }
     });
+    group.on("dblclick", (e) => {
+      if (this.mode !== "select") return;
+      e.cancelBubble = true;
+      this.cb.onPinoutRequested?.(device);
+    });
+
     group.on("dragstart", () => {
       if (this.wireStart) { group.stopDrag(); return; }
       if (device.properties?.locked) { group.stopDrag(); return; }