chore(async search): search per N-minute intervals

[forshev]

Description

search per N-minute intervals instead of per-fraction to support compaction

Fixes #463

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[codecov-commenter]

Codecov Report

❌ Patch coverage is 62.32877% with 55 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.35%. Comparing base (4ad8f17) to head (010fcb2).

Files with missing lines	Patch %	Lines
asyncsearcher/async_searcher.go	57.25%	39 Missing and 14 partials ⚠️
fracmanager/fractions_snapshot.go	87.50%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #471      +/-   ##
==========================================
- Coverage   70.44%   70.35%   -0.10%     
==========================================
  Files         232      232              
  Lines       18371    18448      +77     
==========================================
+ Hits        12942    12979      +37     
- Misses       4453     4481      +28     
- Partials      976      988      +12     

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