feat(core): event queue, Ethernet, switch, ARP, IPv4, ICMP, routing and firewall

First slice of the TypeScript port of the filius-ipad runtime engine,
with 29 tests ported from the Swift suite. Parts not ported yet throw
NotPortedError instead of guessing.

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

packages/core/src/model/node.ts

@@ -0,0 +1,102 @@
+// Ported from filius-ipad (GPLv2/GPLv3):
+//   ios/FiliusPad/TopologyEditor/Model/TopologyNode.swift
+// Java counterpart: filius.hardware.knoten.* (port counts per device kind).
+
+import type { Id } from '../ids.js';
+
+export type NodeKind =
+  | 'pc'
+  | 'notebook'
+  | 'networkSwitch'
+  | 'router'
+  | 'gateway'
+  | 'remoteLink'
+  | 'unsupported';
+
+export function isPcClassEndpoint(kind: NodeKind): boolean {
+  return kind === 'pc' || kind === 'notebook';
+}
+
+export type HostLabelPolicy = 'manual' | 'ipAddress' | 'macAddress' | 'ipAndMAC';
+
+export interface PortMetadata {
+  readonly id: Id;
+  label: string;
+  isOccupied: boolean;
+  /** Canonical (upper case, colon separated) or undefined. */
+  readonly importedMacAddress?: string;
+}
+
+/**
+ * The MAC address of a port nobody gave one: `02:` followed by the last ten
+ * hex digits of the port's UUID — stable across saves, locally administered.
+ */
+export function stableGeneratedMacAddress(portId: Id): string {
+  const compact = portId.toUpperCase().replaceAll('-', '');
+  const suffix = compact.slice(-10);
+  const octets = ['02'];
+  for (let offset = 0; offset < suffix.length; offset += 2) {
+    octets.push(suffix.slice(offset, offset + 2).toUpperCase());
+  }
+  return octets.join(':');
+}
+
+/** Six colon-separated pairs of hex digits, upper-cased; anything else is undefined. */
+export function canonicalMacAddress(value: string | undefined | null): string | undefined {
+  if (value === undefined || value === null) return undefined;
+  const segments = value.trim().split(':');
+  if (segments.length !== 6) return undefined;
+  if (!segments.every((segment) => /^[0-9A-Fa-f]{2}$/.test(segment))) return undefined;
+  return segments.map((segment) => segment.toUpperCase()).join(':');
+}
+
+export function effectiveMacAddress(port: PortMetadata): string {
+  return port.importedMacAddress ?? stableGeneratedMacAddress(port.id);
+}
+
+/**
+ * The name a new device gets. These are the Java FILIUS device names; the
+ * editor shows them translated (packages/editor i18n), the model keeps them
+ * as they appear in a Java .fls file.
+ */
+export function defaultDisplayName(kind: NodeKind): string {
+  switch (kind) {
+    case 'pc':
+      return 'Rechner';
+    case 'notebook':
+      return 'Notebook';
+    case 'networkSwitch':
+      return 'Switch';
+    case 'router':
+      return 'Vermittlungsrechner';
+    case 'gateway':
+      return 'Gateway';
+    case 'remoteLink':
+      return 'Remote Link';
+    case 'unsupported':
+      return 'Unbekanntes Gerät';
+  }
+}
+
+/** Labels of the ports a new device of this kind has, in order. */
+export function defaultPortLabels(kind: NodeKind): string[] {
+  switch (kind) {
+    case 'pc':
+    case 'notebook':
+      return ['eth0'];
+    case 'networkSwitch':
+      // Java Switch constructs exactly 24 physical ports.
+      return Array.from({ length: 24 }, (_, index) => `sw${index + 1}`);
+    case 'router':
+      // Java Vermittlungsrechner starts with one configurable network interface.
+      return ['rt1'];
+    case 'gateway':
+      // Java Gateway has fixed WAN (index 0) and LAN (index 1) interfaces.
+      return ['wan0', 'lan0'];
+    case 'remoteLink':
+      // One local physical attachment, matching the Java Modem.
+      return ['remote0'];
+    case 'unsupported':
+      return [];
+  }
+}