Brings the belt-printer work up to date with 591 upstream commits.
Conflict resolutions (12 files, 42 hunks):
- GCode.cpp: adopted upstream's per-filament/per-nozzle config refactor
(get_filament_config_index, NOZZLE_CONFIG), the extracted
generate_timelapse_gcode + farthest-point timelapse, and the
ConfigOptionFloatsNullable calibration options. Re-applied the belt
hooks on top: init_belt_writer / axis remap / FirstLayerPlane setup,
on_set_origin, the belt-corrected calib_z for the volumetric speed
tower, and path_on_first_layer (belt's per-path first-layer test) in
place of upstream's layer-index on_first_layer() in the acceleration,
jerk and overhang-detection paths. Swept upstream's new m_writer.
uses to m_writer-> since belt holds the writer by unique_ptr.
- interpolate_value_across_layers: kept upstream's banded stepping and
belt's object-Z-span ratio; dropped upstream's duplicate ratio decl.
- Plater.cpp: took upstream's guarded add_model(...) early-returns and
the VFA vfa_layer_height plumbing; kept the belt temp-tower path,
_calib_apply_belt_mode and belt_calib_flip_ringing_tower. Dropped the
VFA "cut upper" block, superseded upstream by model scaling.
- Brim.cpp: upstream's ObjectInstanceID-keyed brimAreaMap, keeping the
belt early-return.
- 3DScene.cpp: kept both the belt build-plate tilt up_direction and
upstream's per-extruder printable-height shading.
- GCodeViewer.cpp: kept upstream's dim-previous-layers setup and belt's
exemption from the same-result early return.
- TreeSupport.cpp: upstream's >= 0 roof-layer fix inside belt's
belt-floor branch.
- calib.cpp / GCode.hpp / GCodeWriter.{cpp,hpp} / Print.hpp: upstream's
additions adapted to belt's pointer-held writer and helpers.
- Custom.json: kept profile version 02.04.00.03 (belt) over upstream's
02.04.00.01; both bumped from 02.04.00.00.
Building this tree needs the wxInspector dependency, which upstream
added in the interim (python3 and wxWidgets 3.3.2 were already present
in the shared deps prefix).
