RESUME fails with "Extrude below minimum temp" when PRINT_START was not used

[Tanguille]

RESUME in macros.cfg heats to _global_var.target_extruder and then extrudes 50 mm:

M109 S{extruder_target_temp}
M83
G1 E50 F300

That variable is only set by PRINT_START and reset to 0 by PRINT_END. If the G-code heats the nozzle directly instead of calling PRINT_START (custom slicer start G-code, older profiles), it stays 0. Every resume then runs M109 S0 and fails on the purge with Extrude below minimum temp, and the print cannot be resumed from the UI. The error gives no hint at the real cause.

Two things make it worse:

• PAUSE lowers the hotend to the probing temperature without saving the previous target, although RESUME already declares an unused variable_last_extruder_temp for that.
• After 30 min _IDLE_TIMEOUT turns the hotend off, so a manual M109 doesn't survive either.

Workaround: SET_GCODE_VARIABLE MACRO=_global_var VARIABLE=target_extruder VALUE=<print temp> then RESUME.

Suggested fix: PAUSE stores printer.extruder.target in last_extruder_temp before cooling; RESUME uses target_extruder, falls back to that saved value, and raises a clear error if both are 0.

Seen on Cosmos release 26.08.0, Kalico 3f166182, Centauri Carbon.