systemd: reduce default service stop timeout to 5s

On ROCKNIX's read-only squashfs root, network services don't need
graceful shutdown — only persistent storage sync matters.  Services
like iwd and systemd-resolved can hang for 90s (the systemd default)
on shutdown/reboot, blocking device access during development and
causing poor user experience on handheld gaming devices.

Changes:
- Add system.conf.d/10-shutdown-timeout.conf with
  DefaultTimeoutStopSec=5s and DefaultTimeoutAbortSec=5s
- Add TimeoutStopSec=1s to iwd.service (matches existing pattern
  used by avahi, bluez, sshd, samba)
- Add TimeoutStopSec=1s to systemd-resolved override

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

projects/ArchR/packages/sysutils/systemd/package.mk

@@ -266,6 +266,10 @@ post_makeinstall_target() {
   safe_remove ${INSTALL}/etc/udev/rules.d
   ln -sf /storage/.config/udev.rules.d ${INSTALL}/etc/udev/rules.d
 
+  # system manager timeout overrides
+  mkdir -p ${INSTALL}/etc/systemd/system.conf.d
+  cp -PR ${PKG_DIR}/config/system.conf.d/* ${INSTALL}/etc/systemd/system.conf.d/
+
   # journald
   ln -sf /storage/.cache/journald.conf.d ${INSTALL}/usr/lib/systemd/journald.conf.d
 }

projects/ROCKNIX/packages/sysutils/systemd/config/system.conf.d/10-shutdown-timeout.conf

@@ -0,0 +1,7 @@
+[Manager]
+# Reduce default service stop timeout from 90s to 5s.
+# ROCKNIX uses a read-only squashfs root with persistent storage at /storage/.
+# Network services don't need graceful shutdown — only filesystem sync matters,
+# which is handled by systemd's built-in shutdown ordering.
+DefaultTimeoutStopSec=5s
+DefaultTimeoutAbortSec=5s