Surface API response bodies on errors

[JordanNoone]

Summary

• read the response body before returning a zoo api HTTP error
• include a non-empty server response in the error message
• format the HTTP status once instead of repeating its reason phrase

Tests

• cargo fmt --check
• focused test target compiled locally; execution requires ZOO_TEST_TOKEN and will run in CI

Closes #1754

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 65.94%. Comparing base (0c27251) to head (f160a9b).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1824   +/-   ##
=======================================
  Coverage   65.94%   65.94%           
=======================================
  Files          43       43           
  Lines        8434     8434           
=======================================
  Hits         5562     5562           
  Misses       2872     2872           

Flag	Coverage Δ
unittests	65.94% <ø> (ø)

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