Purge and check before resuming after a PAUSE

_RESUME_PRINT purges 40 mm with BLOBIFIER_CHECKED (instead of the 2 mm
unretract), so the nozzle is primed, wiped and checked before going back
to the print. A failed purge check raises an error that aborts the whole
resume, AFC_RESUME's restore included, so the printer stays paused; the
next RESUME checks again. RESUME PURGE=0 skips the purge.

The purge check records a failure in _PURGE_CHECK_CFG.last_failed, since
its PAUSE has no effect while the printer is already paused.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

macros/afc/purge_check.cfg

@@ -49,6 +49,7 @@ variable_pressure_min_ms: 5000 # placeholder: longest continuous pressure needed
 variable_bdwidth_warmup_ms: 15000
 variable_start_counts: 0
 variable_start_e: 0.0
+variable_last_failed: False    # last check failed in enforce mode (read by _RESUME_PURGE_VERIFY)
 gcode:
 
 [gcode_macro BLOBIFIER_CHECKED]
@@ -150,6 +151,7 @@ gcode:
         RESPOND MSG="PURGE_CHECK {lane}: {motion}; {press} -> {verdict}"
         {% if failed and cfg.mode == "enforce" %}
             RESPOND TYPE=error MSG="PURGE_CHECK: {lane} {failed|join(', ')} - check extruder and lane"
-            PAUSE
+            SET_GCODE_VARIABLE MACRO=_PURGE_CHECK_CFG VARIABLE=last_failed VALUE=True
+            PAUSE                       ; no effect while already paused (resume purge): see _RESUME_PURGE_VERIFY
         {% endif %}
     {% endif %}