fix(ha): use drbdmeta --force directly; fix T4 grep-c arithmetic bug

cluster-init.sh: replace 'drbdadm create-md --force' with direct drbdmeta
calls using --force on both steps.  drbdadm create-md --force passes --force
to the create-md sub-call but NOT to write-dev-uuid, which then fails when
/dev/sdb is busy and stdin is not a TTY ("stdin not a TTY, not waiting for
confirmation" → exit 20).  write-dev-uuid failing means DRBD has no UUID,
so the peer can't identify the device → connection fails → no sync → wrong
Active node detected by acceptance tests.

acceptance-tests.sh T4: grep -c returns exit code 1 when the count is 0
(no matches), triggering '|| echo "0"' and producing "0\n0" which breaks
[[ "$IQN_COUNT" -ge 1 ]] with "arithmetic syntax error".  Fixed by running
the pipe inside bash -c with '|| true' on the grep to suppress the
non-zero exit code.  Same fix applied to T5's IQN_ON_STANDBY check.

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

scripts/ha/acceptance-tests.sh

@@ -97,7 +97,7 @@ fi
 # ── T4: iSCSI target visible on Active node ───────────────────────────────
 echo ""
 echo "[T4] iSCSI target"
-IQN_COUNT=$(na "ls /sys/kernel/config/target/iscsi/ 2>/dev/null | grep -c iqn" || echo "0")
+IQN_COUNT=$(na "bash -c 'ls /sys/kernel/config/target/iscsi/ 2>/dev/null | grep -c iqn || true'" 2>/dev/null || echo "0")
 if [[ "$IQN_COUNT" -ge 1 ]]; then
   pass "iSCSI IQN active on $ACTIVE_NODE ($IQN_COUNT target(s))"
 else
@@ -130,7 +130,7 @@ done
 
 if $MOVED; then
   pass "XFS mounted on $STANDBY_NODE after failover"
-  IQN_ON_STANDBY=$(ns "ls /sys/kernel/config/target/iscsi/ 2>/dev/null | grep -c iqn" || echo "0")
+  IQN_ON_STANDBY=$(ns "bash -c 'ls /sys/kernel/config/target/iscsi/ 2>/dev/null | grep -c iqn || true'" 2>/dev/null || echo "0")
   [[ "$IQN_ON_STANDBY" -ge 1 ]] \
     && pass "iSCSI target active on $STANDBY_NODE after failover" \
     || fail "iSCSI target NOT active on $STANDBY_NODE after failover"