Add Boost.ContainerHash integration and example

[mborland]

Closes: #436

[cppalliance-bot]

An automated preview of the documentation is available at https://446.int128.prtest3.cppalliance.org/libs/int128/doc/html/index.html

If more commits are pushed to the pull request, the docs will rebuild at the same URL.

2026-07-23 15:30:09 UTC

[codecov]

Codecov Report

❌ Patch coverage is 97.67442% with 3 lines in your changes missing coverage. Please review.
✅ Project coverage is 96.28%. Comparing base (778566a) to head (efa35fb).

Files with missing lines	Patch %	Lines
examples/container_hash.cpp	92.30%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #446      +/-   ##
===========================================
+ Coverage    96.25%   96.28%   +0.02%     
===========================================
  Files           81       83       +2     
  Lines         7139     7268     +129     
  Branches      2484     2560      +76     
===========================================
+ Hits          6872     6998     +126     
  Misses          31       31              
- Partials       236      239       +3     

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.