docs(nexus): add user-facing Nexus docs for Beta release

[dmitryduev]

Fixes

• Fixes WB-NNNNN
• Fixes #NNNN

Description

What does the PR do?

🤖 Generated by Copilot at 338bb0f

This pull request introduces the nexus project, a new Golang implementation of the W&B SDK internal process. It adds a README file for the nexus subdirectory, and an optional dependency to the pyproject.toml file.

Testing

How was this PR tested?

Checklist

• Include reference to internal ticket "Fixes WB-NNNNN" and/or GitHub issue "Fixes #NNNN" (if applicable)
• Ensure PR title compliance with the conventional commits standards

🤖 Generated by Copilot at 338bb0f

nexus project born
Golang and Python in sync
Winter of refactor

[socket-security]

No dependency changes detected. Learn more about Socket for GitHub ↗︎

👍 No dependency changes detected in pull request

[codecov]

Codecov Report

Merging #6276 (9e3ae11) into main (5f70cd8) will decrease coverage by 0.08%.
The diff coverage is 50.00%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6276      +/-   ##
==========================================
- Coverage   77.06%   76.99%   -0.08%     
==========================================
  Files         385      385              
  Lines       44358    44360       +2     
==========================================
- Hits        34185    34154      -31     
- Misses      10120    10153      +33     
  Partials       53       53              

Flag	Coverage Δ
unittest	80.74% <50.00%> (-0.08%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
wandb/sdk/wandb_init.py	86.86% <50.00%> (-0.13%)	⬇️

... and 14 files with indirect coverage changes