refactor(backend): UserBlockingService <-> UserFollowingService 双方向循環を解消

[samunohito]

What

#17412 のサンプルとして、UserBlockingService <-> UserFollowingService の双方向循環参照を解消しました。
データアクセス・キャッシュ保持を責務とした BlockingDataAccessService を作成することで、Blocking / Following がそれぞれ互いを知らなくても良くなりました。

Why

#17412

Additional info (optional)

このprは、「17412をどう実現するのか」のサンプルとしての意味合いが強いです。
そもそもの方針としてダメそうであれば、issue/prともにclose頂けると助かります

Checklist

• Read the contribution guide
• Test working in a local environment
• (If needed) Add story of storybook
• (If needed) Update CHANGELOG.md
• (If possible) Add tests

[github-actions]

このPRによるapi.jsonの差分
差分はありません。
Get diff files from Workflow Page

[codecov]

Codecov Report

❌ Patch coverage is 58.53659% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 24.82%. Comparing base (e6375fb) to head (bfce851).

Files with missing lines	Patch %	Lines
.../src/core/data-access/BlockingDataAccessService.ts	55.55%	11 Missing and 1 partial ⚠️
packages/backend/src/core/UserBlockingService.ts	60.00%	4 Missing ⚠️
packages/backend/src/core/UserFollowingService.ts	66.66%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           develop   #17413   +/-   ##
========================================
  Coverage    24.82%   24.82%           
========================================
  Files         1156     1157    +1     
  Lines        39330    39347   +17     
  Branches     10952    10949    -3     
========================================
+ Hits          9762     9768    +6     
- Misses       23694    23704   +10     
- Partials      5874     5875    +1     

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[github-actions]

Backend memory usage comparison

Before GC

Metric	base (MB)	head (MB)	Diff (MB)	Diff (%)
VmRSS	311.24 MB	296.37 MB	-14.87 MB	-4.77%
VmHWM	311.24 MB	296.37 MB	-14.87 MB	-4.77%
VmSize	23177.34 MB	23162.80 MB	-14.53 MB	-0.06%
VmData	1377.31 MB	1361.41 MB	-15.90 MB	-1.15%

After GC

Metric	base (MB)	head (MB)	Diff (MB)	Diff (%)
VmRSS	311.32 MB	296.37 MB	-14.95 MB	-4.80%
VmHWM	311.32 MB	296.37 MB	-14.95 MB	-4.80%
VmSize	23177.43 MB	23162.80 MB	-14.62 MB	-0.06%
VmData	1377.39 MB	1361.41 MB	-15.98 MB	-1.16%

After Request

Metric	base (MB)	head (MB)	Diff (MB)	Diff (%)
VmRSS	311.74 MB	296.88 MB	-14.86 MB	-4.76%
VmHWM	311.74 MB	296.88 MB	-14.86 MB	-4.76%
VmSize	23177.51 MB	23162.97 MB	-14.53 MB	-0.06%
VmData	1377.48 MB	1361.58 MB	-15.90 MB	-1.15%

See workflow logs for details