ims-pdn-up, imsd: register on the PDN's own address, not the kernel's temporary one

imsd took the first global IPv6 on the ims netdev as its address, and
the kernel lists the temporary (privacy) SLAAC address first: `temporary
dynamic`, preferred for a day and valid for two by its lifetimes (read
2026-09-24). Contact, Via and the four SAs were bound to it, so once the
kernel removes it the registration has lost its address. The address
ModemManager assigned — the one the script installs — sat third on the
list. Seen on the dev phone; a field unit's journal shows the split too
— imsd registered on an address other than the one the script installed
(ims ledger F18).

Hand the assigned address to the daemon as LOCAL through /run/imsd.env,
next to DEV. For a manual run without it, prefer a global address that
is neither `temporary` nor `dynamic`, then any non-temporary one.

A restart after the upgrade finds the registration's SAs on the old
address. It resumes there while that address is still on the link, and
moves to the PDN's address in place: with its next fresh registration,
or when the old address leaves the link first. When the address it is
registered on leaves the netdev and the PDN's own address is not there
to move to, a registered imsd exits at its next recovery step, non-zero,
for a systemd restart, which runs the PDN bring-up again.

Tested on the dev phone (KPN) in builds of this series; not every path
has run there.

packaging/ims-pdn-up.sh

@@ -297,9 +297,13 @@ case "$PCSCF" in
     *)   log "PCSCF '$PCSCF' is not an IPv6 address; the ims PDN is brought up IPv6-only"; exit 1 ;;
 esac
 
-# ---- hand the connected ims netdev to imsd (imsd.service reads
-# /run/imsd.env) so the daemon carries no baked-in interface name
-echo "DEV=$IFACE" > /run/imsd.env
+# ---- hand the connected ims netdev and the PDN's own address to imsd
+# (imsd.service reads /run/imsd.env): the daemon carries no baked-in
+# interface name and registers on the address the network assigned — not
+# on the kernel's temporary SLAAC address from the RA, which the netdev
+# lists first and which is deprecated after a day and removed after two
+# (ims ledger F18; the SAs and the Contact would go with it)
+printf 'DEV=%s\nLOCAL=%s\n' "$IFACE" "$ADDR" > /run/imsd.env
 
 # ---- open the IMS protected ports in the firewall (rung 5b root cause,
 # journal/ims.md s56): pmOS's default nftables INPUT chain is policy-drop and