fix(browser-detector): ensure Node.js v21+ is not detected as browser

[fiyinfoluwa001]

Fixes #6244 Description: > Modern Node.js and Bun runtimes now define a global navigator object. This caused the BrowserDetector to incorrectly identify these environments as browsers. Changes:

Updated isBrowser check to explicitly verify that process.versions.node and Bun.version are undefined.

Added a regression test case in BrowserDetector.test.ts that runs in Node.js to verify an empty resource is returned even when navigator is present.

[linux-foundation-easycla]

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• ✅ login: overbalance / name: Jared Freeze (d9473ec)

[fiyinfoluwa001]

[overbalance]

This code doesn't detect browsers and misses some less popular runtimes and environments. I would recommend the inverse:

typeof window !== 'undefined' && typeof window.document !== 'undefined'

[fiyinfoluwa001]

This makes more sense . I'll update the logic to use feature detection for window and document and verify that the Node.js regression test still passes.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 95.45%. Comparing base (0a9b614) to head (d9473ec).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6271      +/-   ##
==========================================
+ Coverage   95.41%   95.45%   +0.04%     
==========================================
  Files         317      317              
  Lines        9597     9597              
  Branches     2220     2221       +1     
==========================================
+ Hits         9157     9161       +4     
+ Misses        440      436       -4     

Files with missing lines	Coverage Δ
...ntelemetry-browser-detector/src/BrowserDetector.ts	26.66% <100.00%> (+13.33%)	⬆️

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[overbalance]

@fiyinfoluwa001 While testing, I didn't realize I could push to your branch. 🤷 My mistake.

I created a helper function (used elsewhere in OTel) called describeNode and updated the test. I can rollback if you like but I think the new comparison handles more environments.

Removing my review because I unintentionally added code.

[fiyinfoluwa001]

Thank you for the help with describeNode and the environment check refactor! I’ve pulled the changes locally. I appreciate the guidance on following the project's testing standards.

[otelbot]

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