fix(agenda): handle calendar view events that spread across multiple days

[NGPixel]

Fixes #8682

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.80%. Comparing base (70bf2ae) to head (a167f11).
Report is 41 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #8685      +/-   ##
==========================================
- Coverage   88.88%   88.80%   -0.09%     
==========================================
  Files         312      314       +2     
  Lines       40891    41243     +352     
==========================================
+ Hits        36345    36624     +279     
- Misses       4546     4619      +73     

☔ View full report in Codecov by Sentry.
📢 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.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[rjsparks]

Would be nice if we had a set of tests that would track changes like this.

[NGPixel]

We don't test the calendar component (other than opening the modal and validating the buttons around it) because it's an external library.