feat: firewall policy switches and nftables troubleshooting

- Add peer-to-peer and LAN-to-peers switches on the rules page
- Both settings persisted in configurations table and applied
  as nftables chains on toggle
- Add "View nftables Rules" button to dump the live ruleset
  for troubleshooting
- Rules page redesigned with card-based layout matching other
  admin pages
- Rule create/edit/delete events fire as background tasks

wiregui/models/configuration.py

@@ -32,6 +32,10 @@ class Configuration(SQLModel, table=True):
         sa_column=Column(JSON, default=["0.0.0.0/0", "::/0"]),
     )
 
+    # Firewall policies
+    allow_peer_to_peer: bool = Field(default=False)
+    allow_lan_to_peers: bool = Field(default=False)
+
     # Server WireGuard keypair (generated on first startup)
     server_private_key: str | None = None
     server_public_key: str | None = None