feat(orient): auto-orient the largest overhang toward the cooling fan

New printer option fan_direction (undefine/left/right/both, default
undefine) declares which side the auxiliary part-cooling airflow comes
from. When set and the printer has an auxiliary fan, auto-orient adds a
yaw rotation so the dominant overhang area faces the airflow, and newly
added primitive shapes are pre-oriented the same way (except the Cube,
whose axis-aligned bounding box the pressure-advance pattern calibration
depends on).

- FanDirection enum + fan_direction printer option (Accessory group,
  enabled only with auxiliary_fan)
- orient engine: weighted overhang areas per candidate, yaw-direction
  search, vertical rotation applied on top of the primary orientation;
  the cooling weights are taken from the candidate actually chosen,
  including the flat-bottom tie-break
- orient_for_cooling() for primitive placement
- set fan_direction=left on H2C/H2D/H2D Pro/X1/X1E/P1S 0.4 profiles
  (X1C/H2S/P2S/X2D/Qidi X-Max 4 already carried the key, which now
  takes effect)

With fan_direction unset or no auxiliary fan the vertical rotation stays
identity and auto-orient results are unchanged; slicing and g-code are
never affected.

src/libslic3r/Preset.cpp

@@ -1390,7 +1390,7 @@ static std::vector<std::string> s_Preset_printer_options {
     "default_print_profile", "inherits",
     "silent_mode",
     "scan_first_layer", "enable_power_loss_recovery", "wrapping_detection_layers", "wrapping_exclude_area", "machine_load_filament_time", "machine_unload_filament_time", "machine_tool_change_time", "time_cost", "machine_pause_gcode", "template_custom_gcode",
-    "nozzle_type", "nozzle_hrc","auxiliary_fan", "nozzle_volume","upward_compatible_machine", "z_hop_types", "travel_slope", "retract_lift_enforce","support_chamber_temp_control","support_air_filtration","cooling_filter_enabled","printer_structure","farthest_point_timelapse",
+    "nozzle_type", "nozzle_hrc","auxiliary_fan", "fan_direction", "nozzle_volume","upward_compatible_machine", "z_hop_types", "travel_slope", "retract_lift_enforce","support_chamber_temp_control","support_air_filtration","cooling_filter_enabled","printer_structure","farthest_point_timelapse",
     "best_object_pos", "head_wrap_detect_zone",
     "host_type", "print_host", "printhost_apikey", "flashforge_serial_number", "bbl_use_printhost", "printer_agent",
     "print_host_webui",