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>

package.json

@@ -0,0 +1,23 @@
+{
+  "name": "mdg-filius",
+  "private": true,
+  "license": "GPL-3.0-only",
+  "type": "module",
+  "workspaces": [
+    "packages/*"
+  ],
+  "engines": {
+    "node": ">=20"
+  },
+  "scripts": {
+    "test": "vitest run",
+    "typecheck": "tsc -b",
+    "check": "npm run typecheck && npm run test",
+    "hooks": "git config core.hooksPath scripts/hooks"
+  },
+  "devDependencies": {
+    "@types/node": "^20.19.0",
+    "typescript": "^5.9.0",
+    "vitest": "^3.2.0"
+  }
+}