Add MP4 Video File Support

[karlobencic]

Adds full support for signing and validating MP4 video files with C2PA manifests.

• Added support for MP4 video files (mp41, mp42, isom brands)
• Implemented StcoBox and Co64Box classes for proper chunk offset patching when inserting C2PA manifests in MP4 files
• Fixed QuickTime-style MetaBox parsing to handle both ISO BMFF and QuickTime formats
• Fixed JUMBF extraction to exclude trailing padding bytes
• Made metadata assertion JSON-LD parser more lenient with undefined prefixes
• Added MP4 video signing and validation tests
• MP4 files can now be signed and validated using BMFF v2 and v3 hash assertions

[changeset-bot]

🦋 Changeset detected

Latest commit: 2234c27

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@trustnxt/c2pa-ts	Minor

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[cyraxx]

Have the resulting signed MP4s (V2 and V3 assertion) been cross-verified with c2patool?

[karlobencic]

Have the resulting signed MP4s (V2 and V3 assertion) been cross-verified with c2patool?

Both V2 and V3 work with c2patool

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[cyraxx]

Great work!