v3 : Add Full Metadata Parsing for WEBP Animations

[JimBobSquarePants]

Prerequisites

• I have written a descriptive pull-request title
• I have verified that there are no overlapping pull-requests open
• I have verified that I am following the existing coding patterns and practice as demonstrated in the repository. These follow strict Stylecop rules 👮.
• I have provided test coverage for my change (where applicable)

Description

#3001 for the v3.x release

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

[Copilot]

Pull Request Overview

This PR adds full metadata parsing for WEBP animations by extending the Identify method to extract frame-level metadata without decoding pixel data. The implementation enables metadata extraction for both lossless and lossy animated WEBP images, and also addresses resolution metadata parsing from EXIF profiles.

• Adds Identify method to WebpAnimationDecoder for metadata-only parsing of animated WEBP files
• Integrates EXIF resolution metadata into image metadata for WEBP format
• Updates error handling to follow WEBP specification by ignoring unknown chunks instead of throwing exceptions

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
WebpDecoderTests.cs	Adds test cases to verify metadata extraction for animated lossless and lossy WEBP images
WebpDecoderCore.cs	Routes animated WEBP identification through the animation decoder for complete metadata parsing
WebpChunkParsingUtils.cs	Extracts and applies resolution values from EXIF profiles to image metadata
WebpAnimationDecoder.cs	Implements frame metadata parsing in Identify method and adds skipMetadata parameter support
PngFrameMetadata.cs	Corrects documentation from "hundredths" to "seconds" for frame delay specification

---

_{Tip: Customize your code reviews with copilot-instructions.md. Create the file or learn how to get started.}