Enhance resampling logic in SampleSeries to handle interior zero-dura…

[tombonfert]

…tion blocks. Added tests to validate behavior for interior and trailing point-in-time scenarios.

Summary

Changes

Test Plan

• Unit tests added/updated
• Manual testing completed
• Documentation updated (if applicable)

Checklist

• Code follows project style guidelines
• Self-review completed
• No new linter warnings introduced

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.25%. Comparing base (1e7a4a7) to head (b01ed35).

Additional details and impacted files

@@           Coverage Diff           @@
##             main      #40   +/-   ##
=======================================
  Coverage   86.24%   86.25%           
=======================================
  Files          52       52           
  Lines        4166     4168    +2     
  Branches      499      500    +1     
=======================================
+ Hits         3593     3595    +2     
  Misses        477      477           
  Partials       96       96           

Files with missing lines	Coverage Δ
...impulse_query_engine/model/series/sample_series.py	84.45% <100.00%> (+0.07%)	⬆️

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