Force @assetType presence when generating a Key object

[andremacedopv]

This fix makes sure that any call to the NewKey function returns an object with the @key and @assetType properties. Currently, if only the key is sent in the map, the type is never present in the object, affecting the functionality of standard transactions, such as Update Asset.

[Copilot]

Pull Request Overview

This PR fixes a bug in the NewKey function where the @assetType property was not being populated when only a @key was provided in the input map. The fix ensures that both @key and @assetType properties are always present in the returned Key object by extracting the asset type from the key string when it's not explicitly provided.

• Extracts asset type from the @key value when @assetType is not present in the input
• Adds validation to ensure the key format is valid for type extraction
• Includes comprehensive test coverage for both scenarios (with and without explicit asset type)

Reviewed Changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
assets/key.go	Added logic to extract asset type from @key when @assetType is missing
test/assets_key_test.go	Added test cases to verify key generation works with both @assetType and @key inputs

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