v0.5.0-GuppyKE

Added

• Skew Correction panel in the Tune tab, plus a printable skew-calibration frame.
• 0.001 mm Z-offset baby-step option.
• First end-user wiki pages + README refresh.

Fixed

• TMC Metrics crash on TMC2208 drivers (no CoolStep/StallGuard) — guarded; the CoolStep +/- adjusters
  are now hidden on drivers that don't have them.

Changed

• Dropped the bundled skew-calibration g-code — slice your own square instead.