firewall: the module that applies the mesh-computed packet filter (ADR 0050)

The missing applier. mesh-control already derives a node's whole nftables rule
set from the union of its modules' listens and writes it to /etc/nftables.conf;
this module declares filtering:{into} to receive it and loads it — the nftables
service, reloaded on 'filtering' whenever the rules change. A firewall_rules
tool reads the live table so a declared scope can be checked against what is
really enforced. Closes the loop from listens.from to a packet actually dropped.
Manifest parses; tool typechecks.

modules/firewall/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "@novox/module-firewall",
+  "version": "0.1.0",
+  "description": "firewall — applies the mesh-computed packet filter (ADR 0050). Its diagnostic tool lives here.
+  "type": "module",
+  "private": true,
+  "dependencies": {
+    "@novox/mesh-sdk": "^0.1.0"
+  },
+  "devDependencies": {
+    "@types/node": "^22.0.0",
+    "typescript": "^5.6.0"
+  }
+}