fix: routeの定義を共通関数化した

[laminne]

close #1613

What does this PR do?

• routeの定義で作るオブジェクトの共通部分をhelperに分離
• helperを使って全定義を置き換え

Additional information

• 手元でAPI定義の出力に差分が無いことをチェック済みです

[codecov]

Codecov Report

❌ Patch coverage is 0% with 36 lines in your changes missing coverage. Please review.
✅ Project coverage is 45.33%. Comparing base (c6281af) to head (b37688a).

Files with missing lines	Patch %	Lines
pkg/internal/router/helper.ts	0.00%	16 Missing ⚠️
pkg/accounts/router.ts	0.00%	12 Missing ⚠️
pkg/timeline/router.ts	0.00%	4 Missing ⚠️
pkg/notes/router.ts	0.00%	3 Missing ⚠️
pkg/drive/router.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1726      +/-   ##
==========================================
- Coverage   45.53%   45.33%   -0.21%     
==========================================
  Files         159      160       +1     
  Lines        5749     5775      +26     
  Branches      927      932       +5     
==========================================
  Hits         2618     2618              
- Misses       3131     3157      +26     

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