Add converge-wake.service and systemd-sleep hook for wake-from-sleep sync

Creates a oneshot user service (converge-wake.service) that runs
converge --sync after the network is online, and a systemd-sleep hook
(/usr/lib/systemd/system-sleep/converge-wake) that triggers the service
for each logged-in user on resume.

Uses After=network-online.target for proper network timing on
NetworkManager/systemd-networkd setups, with a 5-second ExecStartPre
delay as a safety net for netctl and other environments where
network-online.target may not gate on resume.

Updated PKGBUILD and AGENTS.md accordingly.

converge-wake.service

@@ -0,0 +1,19 @@
+[Unit]
+Description=Converge - sync repos after waking from sleep
+Documentation=https://github.com/jbrechtel/converge
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=oneshot
+ExecStart=/usr/bin/converge --sync
+# Small delay as a safety net for environments (e.g. netctl) where
+# network-online.target may not gate properly on resume, giving the
+# network stack time to reconnect before converge attempts to pull.
+ExecStartPre=/bin/sleep 5
+
+# Allow notify-send to reach the desktop session
+Environment=DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/%U/bus
+
+[Install]
+WantedBy=default.target