Archive and deprecate `cdlclient` package

[PierreRaybaut]

✨ Objective

The cdlclient package was originally developed as a minimal XML-RPC client to control a running instance of DataLab remotely. With the introduction of the datalab-processing package, which now integrates this functionality, cdlclient is no longer required as a separate package.

This issue tracks the formal deprecation, archival, and documentation update for the package.

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📦 Deprecation Plan

• [ ] Mark the cdlclient repository as archived on GitHub
• [ ] Add a deprecation notice in the README, linking to datalab-processing
• [ ] Unpublish (or yanked) the cdlclient PyPI package (optional / low priority)
• [ ] Update all relevant documentation (DataLab main repo, website, etc.) to remove references to cdlclient

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🔁 Successor

The simple XML-RPC client logic previously contained in cdlclient is now integrated into the datalab-processing package (under the rpc module). This ensures:

• Single point of maintenance
• Better alignment with future API changes
• Simpler usage patterns and packaging

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📌 Context

The removal of cdlclient reduces the number of standalone packages and aligns with the broader restructuring of the DataLab ecosystem.

• GUI → datalab-app
• Processing + I/O + RPC → datalab-processing
• GUI foundations → datalab-tools

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🔗 Related

• #166