feat: store .remote-info for remote shards to avoid extra S3

[eguguchkin]

Fixes #435

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• I have read and followed all requirements in CONTRIBUTING.md;
• I used LLM/AI assistance to make this pull request;

[github-actions]

🔴 Performance Degradation

Some benchmarks have degraded compared to the previous run.
Click on Show table button to see full list of degraded benchmarks.

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Name	Previous	Current	Ratio	Verdict
AggWide/size=1000000-4	8fb975	01db29
	469.00 B/op	545.00 B/op	1.16	🔴
MutexListAppend-4	8fb975	01db29
	215.03 MB/s	193.50 MB/s	0.90	🔴

[github-actions]

🔴 Performance Degradation

Some benchmarks have degraded compared to the previous run.
Click on Show table button to see full list of degraded benchmarks.

Show table

Name	Previous	Current	Ratio	Verdict
MutexListAppend-4	8fb975	a8fa9b
	215.03 MB/s	192.22 MB/s	0.89	🔴

[codecov-commenter]

Codecov Report

❌ Patch coverage is 56.29630% with 59 lines in your changes missing coverage. Please review.
✅ Project coverage is 70.86%. Comparing base (df680ff) to head (b937622).
⚠️ Report is 2 commits behind head on main.

Files with missing lines	Patch %	Lines
frac/sealed.go	38.59%	23 Missing and 12 partials ⚠️
frac/remote.go	60.00%	15 Missing and 9 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #436      +/-   ##
==========================================
+ Coverage   70.81%   70.86%   +0.04%     
==========================================
  Files         225      225              
  Lines       17498    17535      +37     
==========================================
+ Hits        12392    12426      +34     
+ Misses       4182     4181       -1     
- Partials      924      928       +4     

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