v4 : Add Full Metadata Parsing for WEBP Animations

[JimBobSquarePants]

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Description

Fixes#2992
Fixes#2988 (I wasn't using up my LFS budget for a separate run)

[Copilot]

Pull Request Overview

This PR adds comprehensive metadata parsing support for WebP animated images, addressing issues #2992 and #2988. The changes enable full frame metadata extraction during the Identify operation for animated WebP files, bringing animation metadata handling to parity with full decode operations.

Key Changes:

• Implemented Identify method in WebpAnimationDecoder to extract frame metadata without full image decoding
• Enhanced segment integrity handling with configurable validation for EXIF/XMP chunks
• Added resolution metadata extraction from EXIF profiles during WebP decoding

Reviewed Changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
WebpDecoderTests.cs	Added test cases to verify frame metadata extraction via Identify for both lossless and lossy animated WebP images
WebpImageInfo.cs	Added DataSize property to track encoded image data size
WebpDecoderCore.cs	Integrated animation decoder into Identify path and added configurable segment integrity handling
WebpChunkParsingUtils.cs	Enhanced optional chunk parsing with EXIF resolution extraction and segment integrity validation
WebpAnimationDecoder.cs	Implemented new Identify method and added ReadFrameInfo helper for metadata-only parsing
PngFrameMetadata.cs	Fixed documentation error: changed "hundredths" to "seconds" for frame delay description

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