Gallery Block: Fix equal column gallery image sizes

[mukeshpanchal27]

Summary

Part of #2449

Relevant Technical Choices

Ensure that the number of images added matches the Gallery block's configured column count.

How to Test

1. Add a Gallery block.
2. Insert 3 images and make sure the Columns setting is set to 3.
3. Verify that the image sizes.
4. Repeat the test with 6 images while keeping the Columns setting at 3.
5. Verify that the image sizes.

Before

After

In follow-up PR will fix the sizes for other column settings.

• Add unit tests

Use of AI Tools

N/A

[codecov]

Codecov Report

❌ Patch coverage is 52.63158% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.10%. Comparing base (b1608b2) to head (46bfea1).

Files with missing lines	Patch %	Lines
...ns/auto-sizes/includes/improve-calculate-sizes.php	52.63%	9 Missing ⚠️

Additional details and impacted files

@@                      Coverage Diff                       @@
##           feature/2449-gallery-block    #2534      +/-   ##
==============================================================
- Coverage                       69.14%   69.10%   -0.05%     
==============================================================
  Files                              90       90              
  Lines                            7723     7742      +19     
==============================================================
+ Hits                             5340     5350      +10     
- Misses                           2383     2392       +9     

Flag	Coverage Δ
multisite	69.10% <52.63%> (-0.05%)	⬇️
single	35.54% <52.63%> (+0.04%)	⬆️

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[mukeshpanchal27]

@westonruter I'd appreciate any initial feedback you can provide on the PR when you have a chance to take a look.

[adamsilverstein]

pr makes sense to me, it would be good to add some tests that demonstrate what it achieves.

[westonruter]

@mukeshpanchal27 How does this handle the responsive layout? If I add a Gallery with three columns I have this on desktop:

But on mobile it becomes 2 columns, and the third image is twice as wide as the first two:

There would seem to need to be some logic add this breakpoint in sizes, where if there is an odd number of images, the last one would get a 100vw width.

[mukeshpanchal27]

@westonruter In 46bfea1 i set two column layout for mobile explicitly.

In follow-up PR will fix issue for different columns.

[westonruter]

We can't rely on wp_is_mobile(), unfortunately. Page caching may not vary responses by device form factor. We'll need a solution that serves the same markup to all devices (the promise of responsive design).