mount_ecrypt_home: wait for FUSE mount before removing passfile

systemd-run service mode returns as soon as the start request is
accepted, before gocryptfs has read the passfile. Poll /proc/mounts
for up to 10 seconds so the passfile is only removed after the mount
is confirmed.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

system_setup/mount_ecrypt_home.sh

@@ -99,7 +99,14 @@ systemd-run --user --unit=gocryptfs-home \
     --property=TimeoutStopSec=30 \
     gocryptfs -noprealloc -allow_other -passfile ${XDG_RUNTIME_DIR}/IPAVAULTKEY -config ${HOME}/.config/gocryptfs/gocryptfs.conf ${ENCRYPTEDDATADIR} ${DECRYPTEDDATADIR} >/dev/null
 RETVAL=$?
-rm ${XDG_RUNTIME_DIR}/IPAVAULTKEY
+# Service starts asynchronously - wait for the FUSE mount to appear before removing
+# the passfile, otherwise gocryptfs may not have read it yet
+_t=0
+while [ "${_t}" -lt 10 ] && ! grep -q "${DECRYPTEDDATADIR}" /proc/mounts 2>/dev/null; do
+    sleep 1
+    _t=$((_t + 1))
+done
+rm -f ${XDG_RUNTIME_DIR}/IPAVAULTKEY
 cd ${EXECDIR}
 if [ ${RETVAL} -eq 0 ]; then
     echo "Sucessfully mounted encrypted private Directory ${DECRYPTEDDATADIR}"