Feat: Add group categories to all macros for Mainsail/Fluidd UI

Calibration macros (calibration/*.cfg):
- All calibration macros grouped under 'Calibration'

Printing macros (user_settings_clean.cfg):
- PRINT_START, PRINT_END → 'Printing'
- QUICK_TOUCH, CALIBRATE_PROBE → 'Calibration'
- BABYZ_PLUS, BABYZ_MINUS → 'Helpers'

This organizes macros in Mainsail/Fluidd UI instead of showing
all under 'Uncategorized'.

user_settings_clean.cfg

@@ -79,6 +79,7 @@ runout_gcode:
 # ============================================================================
 
 [gcode_macro PRINT_START]
+group: Printing
 gcode:
     #--- Setup & Reset ---
     M117 Setting up parameters...
@@ -133,6 +134,7 @@ gcode:
 # ============================================================================
 
 [gcode_macro PRINT_END]
+group: Printing
 gcode:
     M117 Finishing print...
     RESPOND MSG="Print completed! Finishing up..."
@@ -163,6 +165,7 @@ gcode:
 
 [gcode_macro QUICK_TOUCH]
 description: Quick Z measurement with Cartographer
+group: Calibration
 gcode:
     {% if printer.toolhead.homed_axes != "xyz" %}
         G28
@@ -172,6 +175,7 @@ gcode:
 
 [gcode_macro CALIBRATE_PROBE]
 description: Manual Z-offset calibration
+group: Calibration
 gcode:
     {% if printer.toolhead.homed_axes != "xyz" %}
         G28
@@ -180,10 +184,12 @@ gcode:
     CARTOGRAPHER_CALIBRATE
 
 [gcode_macro BABYZ_PLUS]
+group: Helpers
 gcode:
     SET_GCODE_OFFSET Z_ADJUST=0.005 MOVE=1
 
 [gcode_macro BABYZ_MINUS]
+group: Helpers
 gcode:
     SET_GCODE_OFFSET Z_ADJUST=-0.005 MOVE=1