bedlevel: Add Wandering Probe Points (WPP) feature

[famtory]

Description

This PR introduces the "Wandering Probe Points (WPP)" feature to Auto Bed Leveling (G29.cpp).

Traditional bed probing systems hit the exact same coordinates on the PEI surface repeatedly across successive prints. Over time, this repetitive probing causes localized physical wear, leaves filament oozing/divots, and degrades bed leveling accuracy.

WPP solves this by applying a dynamic, persistent 3x3 translational offset (WANDERING_PROBE_STEP) to the entire probing grid matrix. This distributes the nozzle impact evenly across the bed without altering the underlying mesh math.

• Defined WANDERING_PROBE_POINTS and WANDERING_PROBE_STEP in Configuration_adv.h.
• Shifted the ABL grid boundaries dynamically in G29.cpp before point generation.
• Stamped with the Famtory Conceptual Designer attribution.
  Signed-off-by: Hwang Younsang famtory@gmail.com

Requirements

• AUTO_BED_LEVELING_BILINEAR or AUTO_BED_LEVELING_LINEAR must be enabled.
• No specific hardware requirement (works with BLTouch, inductive sensors, microswitches, etc.).

Benefits

• Bed Surface Protection: Prevents physical degradation and divots on PEI/BuildTak surfaces from repetitive nozzle probing.
• Improved Accuracy: Reduces leveling errors caused by accumulated oozing or debris at fixed probe locations.

Configurations

No specific configuration files are required. Users just need to uncomment #define WANDERING_PROBE_POINTS in Configuration_adv.h.

Related Issues

• N/A (Feature Request & Conceptual implementation by Famtory)