feat(editor): F4.5e a router's connections in the device sheet

SheetRun now clicks through Java's JConnectionsDialog with a router, a
computer and a switch cabled in the GUIContainer: a click marks a card,
the same click unmarks it, another card swaps the cables or moves the
one; "+" adds 192.168.0.10/24 up to eight cards, "-" removes the last
card with its cable down to none, and a router without a card keeps no
gateway.

The document adds, removes and swaps a router's cards (the same cables,
the same devices), Java's click logic is one function for the test and
the page, and the sheet names the address at a cable's far end. The
page "Verbindungen verwalten" shows Java's RJ45 buttons in Java's
colours with each card's far end below. Not adopted: the last card
stays. A card tab or a mark whose card is undone away falls back.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/editor/src/sheet/SheetField.tsx

@@ -110,3 +110,16 @@ export function SheetCheck({
     </label>
   );
 }
+
+/** A text with Java's line breaks as paragraphs. */
+export function SheetNote({ text }: { readonly text: string }) {
+  return (
+    <>
+      {text.split('\n').map((line, index) => (
+        <p key={index} className="sheet-note">
+          {line}
+        </p>
+      ))}
+    </>
+  );
+}