M1: compat layer + pf.ko skeleton builds against Linux 7.3.4

- pfk.h: BSD types/ioctl encoding (OpenBSD bit layout), locks (NET_LOCK=rwsem),
  pools, timeouts, mbuf shim over sk_buff, ifnet registry, toeplitz/siphash
- pfk_mod/pfk_hooks: misc /dev/pf (0600), IPv4 netfilter hook skeleton,
  DIOCGETSTATUS answered (M1 skeleton; engine ioctls land with pf_ioctl.c)
- vendorize/stage-port scripts: deterministic upstream staging with seds
  (struct renames, IFF_*->PFIFF_*, sa_len drops) logged to docs/porting-notes
- fixes: modules_prepare+Module.symvers for out-of-tree builds

module/pfsrc/pfk_hooks.c

@@ -0,0 +1,92 @@
+/*
+ * PF-on-Linux netfilter hook registration + M1 ioctl skeleton.
+ * The real verdict logic arrives from staged pf.c (T12); this file owns
+ * hook lifecycle and /dev/pf dispatch. (ISC 2026)
+ */
+#include <pfk.h>
+#include <pfk_api.h>
+#include <net/pfvar.h>
+#include <net/pfvar_priv.h>
+
+static int pfk_enabled = 1;	/* like pf_defaultwise/pf_enable on boot */
+static struct pf_status pfk_stat;
+
+/* --- temporary M1 control surface (replaced by staged pf_ioctl.c, T7b) --- */
+static int pfk_ioctl_min(struct file *f, unsigned int cmd, unsigned long addr)
+{
+	struct pf_status s;
+
+	switch (cmd) {
+	case DIOCGETSTATUS:
+		memset(&s, 0, sizeof(s));
+		s.running = pfk_enabled;
+		strscpy(s.ifname, "pf", sizeof(s.ifname));
+		if (copy_to_user((void __user *)addr, &s, sizeof(s)))
+			return EFAULT;
+		return 0;
+	default:
+		/* Rule/state/table ioctls arrive with the staged pf_ioctl.c
+		 * (plan T7b); until then they are rejected (not silently
+		 * accepted) so behaviour is explicit. */
+		return EINVAL;
+	}
+}
+
+long pfk_ioctl(struct file *f, unsigned int cmd, unsigned long addr)
+{
+	return pfk_ioctl_min(f, cmd, addr);
+}
+
+void pfk_status(struct pf_status *s)
+{
+	if (s)
+		*s = pfk_stat;
+}
+int pfk_enable(int on) { pfk_enabled = on ? 1 : 0; return 0; }
+
+/* --- netfilter hooks: ingress/egress plumbing (real work lands in T12) --- */
+static unsigned int
+pfk_ipv4_hook(void *priv, struct sk_buff *skb, const struct nf_hook_state *st)
+{
+	/* PFLINUX M1: accept-everything placeholder; T12 routes to pf_test() */
+	return NF_ACCEPT;
+}
+
+static struct nf_hook_ops pfk_hooks[] = {
+	{ .hook = pfk_ipv4_hook, .pf = NFPROTO_IPV4, .hooknum = NF_INET_PRE_ROUTING,
+	  .priority = NF_IP_PRI_FIRST },
+	{ .hook = pfk_ipv4_hook, .pf = NFPROTO_IPV4, .hooknum = NF_INET_LOCAL_IN,
+	  .priority = NF_IP_PRI_FIRST + 1 },
+	{ .hook = pfk_ipv4_hook, .pf = NFPROTO_IPV4, .hooknum = NF_INET_FORWARD,
+	  .priority = NF_IP_PRI_FIRST },
+	{ .hook = pfk_ipv4_hook, .pf = NFPROTO_IPV4, .hooknum = NF_INET_LOCAL_OUT,
+	  .priority = NF_IP_PRI_CONNTRACK + 1 },
+	{ .hook = pfk_ipv4_hook, .pf = NFPROTO_IPV4, .hooknum = NF_INET_POST_ROUTING,
+	  .priority = NF_IP_PRI_LAST - 1 },
+};
+#define PFK_NHOOKS ARRAY_SIZE(pfk_hooks)
+
+int pfk_hooks_register(void)
+{
+	int i, err;
+
+	for (i = 0; i < PFK_NHOOKS; i++) {
+		pfk_hooks[i].priv = NULL;
+		err = nf_register_net_hook(&init_net, &pfk_hooks[i]);
+		if (err)
+			goto fail;
+	}
+	return 0;
+fail:
+	while (--i >= 0)
+		nf_unregister_net_hook(&init_net, &pfk_hooks[i]);
+	return err;
+}
+
+void pfk_hooks_unregister(void)
+{
+	int i;
+
+	for (i = 0; i < PFK_NHOOKS; i++)
+		nf_unregister_net_hook(&init_net, &pfk_hooks[i]);
+}