M2: live netfilter data path (pf_test per direction), pfattach bring-up, NET_LOCK reentrancy fix, static pfctl

- pfk_hooks: PRE→PF_IN, LOCAL_OUT/POST→PF_OUT v4+v6; replacement/buffer
  handling with NF_STOLEN + re-injection (documented divergence: re-entry)
- pfk_mod: pf_status_init/pfattach + pfi attach via pfk_if event callback
- pfk_kern: NET_LOCK holder reentrancy (fix deadlock when notifier fires
  under the write lock — observed as full-VM network hang)
- tools: static pfctl link for musl VMs

module/include/pfk_mbuf.h

@@ -141,6 +141,8 @@ struct mbuf {
 struct mbuf *m_get(int how, short type);
 struct mbuf *m_gethdr(int how, short type);
 struct mbuf *m_alloc_skb(struct sk_buff *skb, int how); /* wrap borrowed skb */
+struct mbuf *pfk_m_wrap_skb(struct sk_buff *skb, int af); /* ingress: extra ref */
+struct mbuf *pfk_m_wrap_skb(struct sk_buff *skb, int af); /* ingress: takes extra ref */
 struct mbuf *m_devget(char *buf, int totlen, int off,
 		      struct pfk_ifnet *ifp, void (*copyin_fc)(caddr_t, int));
 void  pfk_m_setpkthdr(struct mbuf *m);