[WIP] Add user agent with package version for hub calls

[Copilot]

• [ ] Create a utility function to wrap fetch and add user-agent header
• [ ] Add package version constant in consts.ts
• [ ] Implement the createFetch function in a new utils file
• [ ] Add tests to verify the user agent is being set correctly
• [ ] Update documentation if necessary
• [ ] Final testing and verification

Fixes #899.

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