Do not encode WEBP images exceeding max dimensions

[JimBobSquarePants]

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Description

Fixes #2920

[Copilot]

Pull Request Overview

Adds a centralized dimension check for WEBP encoding and aligns boundary behavior with JPEG.

• Introduces ThrowDimensionsTooLarge in WebpThrowHelper for uniform errors.
• Adds a guard in WebpEncoderCore to block overly large images.
• Removes duplicate checks in Vp8LEncoder and updates JPEG’s boundary condition.

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

File	Description
WebpThrowHelper.cs	New ThrowDimensionsTooLarge method for WEBP dimension errors
WebpEncoderCore.cs	Guard against Width/Height > MaxDimension before encoding
Lossless/Vp8LEncoder.cs	Removed redundant Guard.MustBeLessThan calls in WriteImageSize
JpegEncoderCore.cs	Switched from >= to > when comparing dimensions to max value

Comments suppressed due to low confidence (4)

src/ImageSharp/Formats/Webp/WebpEncoderCore.cs:135

• Add unit tests to verify that images exceeding WebpConstants.MaxDimension correctly trigger ImageFormatException via ThrowDimensionsTooLarge.

if (image.Width > WebpConstants.MaxDimension || image.Height > WebpConstants.MaxDimension)

src/ImageSharp/Formats/Webp/Lossless/Vp8LEncoder.cs:373

• [nitpick] Consider invoking WebpThrowHelper.ThrowDimensionsTooLarge here if inputs exceed MaxDimension, to keep error handling consistent and avoid relying solely on upstream guards.

private void WriteImageSize(int inputImgWidth, int inputImgHeight)

src/ImageSharp/Formats/Jpeg/JpegEncoderCore.cs:61

• Update or add tests covering the changed boundary condition (> instead of >=) to ensure the new logic matches the intended maximum dimension behavior.

if (image.Width > JpegConstants.MaxLength || image.Height > JpegConstants.MaxLength)

src/ImageSharp/Formats/Webp/WebpThrowHelper.cs:22

• Align the indentation of the new ThrowDimensionsTooLarge method with existing members (six spaces) to match the class’s formatting conventions.

[DoesNotReturn]