docs: add deployment guide

[tabathad]

Part of #1325, complements #1335.

Adds a deployment guide covering:

• Prerequisites
• Quick start walkthrough
• Docker deployment
• Git client configuration
• Production considerations

Also adds the deployment page to the docs sidebar.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.34%. Comparing base (2150064) to head (c3cf454).
⚠️ Report is 69 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1385      +/-   ##
==========================================
- Coverage   81.35%   81.34%   -0.01%     
==========================================
  Files          65       65              
  Lines        4639     4648       +9     
  Branches      792      792              
==========================================
+ Hits         3774     3781       +7     
- Misses        850      852       +2     
  Partials       15       15              

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[jescalada]

Looks good so far! Just wondering if we could look into the config loading issue - although it might be because I tested on v1.19.2 rather than the latest rc...

As for the Docker part, I'll do some more setup testing later so we can refine this 👍🏼

[jescalada]

Oddly, this command doesn't seem to be correctly loading the config on my end. When calling git-proxy --validate, I see that the config file being loaded is ~/.nvm/versions/node/v22.13.1/lib/node_modules/@finos/git-proxy/proxy.config.json which is not the "current working directory" that's mentioned in the option description...

I wonder if this is exclusive to the GitProxy global install and if there's an easy way to fix it.

[jescalada]

We might want to include a link to the auth documentation in the architecture guide: https://github.com/finos/git-proxy/blob/1e98d9dbef27f6e338cf18354b0bbbc418b8a070/docs/Architecture.md#Authentication

The proper link will be available after that PR is merged!