Add cross-dimension shape validation for diff prepend/append

[srinjoy933]

This PR introduces explicit cross-dimension shape validation for the prepend and append arguments in the diff_2 routine. Previously, passing an array with a mismatched non-differencing dimension bypassed shape checks, leading to potential bounds-check faults or silent memory corruption during the internal work array assignment. The update verifies size(array, 3 - dim_) == size(x, 3 - dim_) prior to workspace allocation, ensuring safe execution.
Solves #1151

[srinjoy933]

@jvdp1 @jalvesz please review this pr once, kindly give me your suggestions whether any changes are required or not. Thank You!

[Copilot]

Pull request overview

Adds explicit cross-dimension (non-differencing dimension) shape validation for diff_2’s optional prepend/append arguments to prevent out-of-bounds assignment/memory corruption scenarios described in #1151.

Changes:

• Validate size(prepend, 3-dim_) == size(x, 3-dim_) before using prepend in the internal workspace.
• Validate size(append, 3-dim_) == size(x, 3-dim_) before using append in the internal workspace.

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[srinjoy933]

hey @jalvesz according to the suggestion you have given I have raised a updated pr. Please have a look on this and suggest if there is requirement of any further changes

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 68.00%. Comparing base (ac98d3b) to head (99a460a).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1152   +/-   ##
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  Coverage   68.00%   68.00%           
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  Files         404      404           
  Lines       12935    12935           
  Branches     1392     1392           
=======================================
  Hits         8797     8797           
  Misses       4138     4138           

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[jvdp1]

thank you @srinjoy933 . LGTM!