🚸 Machine-relative Z_STEPPER_ALIGN_XY (#24261)

Co-authored-by: Scott Lahteine <thinkyhead@users.noreply.github.com>

Marlin/Configuration_adv.h

  */
 //#define Z_STEPPER_AUTO_ALIGN
 #if ENABLED(Z_STEPPER_AUTO_ALIGN)
-  // Define probe X and Y positions for Z1, Z2 [, Z3 [, Z4]]
-  // If not defined, probe limits will be used.
-  // Override with 'M422 S<index> X<pos> Y<pos>'
+  /**
+   * Define probe X and Y positions for Z1, Z2 [, Z3 [, Z4]]
+   * These positions are machine-relative and do not shift with the M206 home offset!
+   * If not defined, probe limits will be used.
+   * Override with 'M422 S<index> X<pos> Y<pos>'.
+   */
   //#define Z_STEPPER_ALIGN_XY { {  10, 190 }, { 100,  10 }, { 190, 190 } }
 
   /**

Marlin/src/gcode/calibrate/G34_M422.cpp

           // Safe clearance even on an incline
           if ((iteration == 0 || i > 0) && z_probe > current_position.z) do_blocking_move_to_z(z_probe);
 
+          xy_pos_t &ppos = z_stepper_align.xy[iprobe];
+
           if (DEBUGGING(LEVELING))
-            DEBUG_ECHOLNPGM_P(PSTR("Probing X"), z_stepper_align.xy[iprobe].x, SP_Y_STR, z_stepper_align.xy[iprobe].y);
+            DEBUG_ECHOLNPGM_P(PSTR("Probing X"), ppos.x, SP_Y_STR, ppos.y);
 
           // Probe a Z height for each stepper.
           // Probing sanity check is disabled, as it would trigger even in normal cases because
           // current_position.z has been manually altered in the "dirty trick" above.
-          const float z_probed_height = probe.probe_at_point(z_stepper_align.xy[iprobe], raise_after, 0, true, false);
+          const float z_probed_height = probe.probe_at_point(DIFF_TERN(HAS_HOME_OFFSET, ppos, xy_pos_t(home_offset)), raise_after, 0, true, false);
           if (isnan(z_probed_height)) {
             SERIAL_ECHOLNPGM("Probing failed");
             LCD_MESSAGE(MSG_LCD_PROBING_FAILED);