Fix animated WebP crop artifacts

[ChiragAgg5k]

Summary

• crop animated images by coalescing frames first, then resizing each full frame, then deconstructing — previously only GIF got this treatment
• animated WebP (and any other multi-frame format) was resized as static frames, which scaled delta/partial frames independently and produced blocky ghosting artifacts
• add a regression fixture + test that asserts correct per-frame colors after cropping an animated WebP with dirty rectangles

Before / After

Resizing an animated WebP without coalescing scaled each delta/partial frame independently, which produced blocky ghosting. After this fix, frames are coalesced before resize so mid-animation frames stay clean.

Before (broken remote resize)	After (fixed coalesce + crop)

Frame 10 from an animated WebP resized to height 256 (broken remote preview vs fixed local crop path).

Testing

• ./vendor/bin/phpunit --filter 'test_crop_animated_webp_preserves_frames|test_crop100x100_gif|test_gif_small_last_frame|test_crop_gravity' (31 tests, 180 assertions)
• composer lint
• composer check

[greptile-apps]

Greptile Summary

This PR fixes crop handling for animated WebP and other multi-frame images. The main changes are:

• Coalesce multi-frame images before cropping each frame.
• Reset cropped frame pages to the target canvas size.
• Avoid deconstructing frames after crop.
• Add animated WebP and hold-frame crop tests.

Confidence Score: 5/5

This looks safe to merge.

• No blocking issues found in the changed code.

Important Files Changed

Filename	Overview
src/Image/Image.php	Updates crop logic so multi-frame images are processed frame-by-frame after coalescing, without deconstructing the result.
tests/Image/ImageTest.php	Adds tests for animated WebP crop output and preserved playback delay for repeated hold frames.
tests/resources/disk-a/anim-delta.webp	Adds an animated WebP fixture for dirty-rectangle crop coverage.

_{Reviews (2): Last reviewed commit: "fix: skip deconstruct after animated cro..." | Re-trigger Greptile}