GEOPY-3010: Revert topography definition to cell bottom for DC and MT inversions

[domfournier]

GEOPY-3010 - Revert topography definition to cell bottom for DC and MT inversions

[Copilot]

Pull request overview

This PR adjusts how active cells are computed beneath topography by switching the topography reference from cell centers to cell bottoms for a subset of inversions, and updates regression targets accordingly to match the new inversion results.

Changes:

• Update active_from_xyz(..., grid_reference=...) to use "bottom" when forced_to_surface is enabled.
• Refresh hard-coded regression targets across DC/MT/IP-related run tests to match updated outputs.
• Format diagnostic printing in check_target using scientific notation for easier comparison/debugging.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
tests/utils/targets.py	Formats printed output metrics in scientific notation.
tests/run_tests/driver_mt_test.py	Updates MT inversion regression target values.
tests/run_tests/driver_joint_cross_gradient_test.py	Updates joint inversion regression targets and expected scaling/multiplier arrays.
tests/run_tests/driver_ip_test.py	Updates IP 3D regression target values.
tests/run_tests/driver_ip_2d_test.py	Updates IP 2D regression target values.
tests/run_tests/driver_dc_test.py	Updates DC 3D regression target values.
tests/run_tests/driver_dc_2d_test.py	Updates DC 2D regression target values.
tests/run_tests/driver_dc_2d_rotated_gradients_test.py	Updates DC rotated-gradients regression target values.
simpeg_drivers/components/topography.py	Changes active-cell masking to reference cell bottoms (conditional on forced_to_surface).

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[gmcga]

Looks good as long as the tests are passing.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.29%. Comparing base (295f324) to head (f78dbf5).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #455      +/-   ##
===========================================
+ Coverage    90.27%   90.29%   +0.02%     
===========================================
  Files          113      113              
  Lines         7020     7020              
  Branches       865      865              
===========================================
+ Hits          6337     6339       +2     
+ Misses         466      465       -1     
+ Partials       217      216       -1     

Files with missing lines	Coverage Δ
simpeg_drivers/components/topography.py	92.98% <ø> (ø)

... and 1 file with indirect coverage changes

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