perf: reduce Context code

[yusukebe]

Don't optimize, but reduce the code.

The author should do the following, if applicable

• Add tests
• Run tests
• bun run format:fix && bun run lint:fix to format the code
• Add TSDoc/JSDoc to document the code

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 91.28%. Comparing base (bb7afac) to head (20f0df9).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4100      +/-   ##
==========================================
- Coverage   91.34%   91.28%   -0.07%     
==========================================
  Files         168      168              
  Lines       10704    10737      +33     
  Branches     3070     3161      +91     
==========================================
+ Hits         9778     9801      +23     
- Misses        925      935      +10     
  Partials        1        1              

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[yusukebe]

Whether we merge this or not is a difficult thing. In the c.header(), using c.res to store the header values will introduce a significant decrease in performance when using c.header(). Hmm.

[github-actions]

Bundle size check

	main (bb7afac)	#4100 (4f6f07e)	+/-
Bundle Size (B)	18,979B	18,162B	-817B
Bundle Size (KB)	18.53K	17.74K	-0.79K

Compiler Diagnostics

	main (bb7afac)	#4100 (4f6f07e)	+/-
Files	261	261	0
Lines	116,440	116,369	-71
Identifiers	114,437	114,398	-39
Symbols	303,855	303,786	-69
Types	214,832	214,826	-6
Instantiations	3,091,594	3,091,596	2
Memory used	447,620K	444,290K	-3,330K
I/O read	0.02s	0.02s	0s
I/O write	0s	0s	0s
Parse time	0.63s	0.67s	0.04s
Bind time	0.28s	0.28s	0s
Check time	5.5s	5.55s	0.05s
Emit time	0s	0s	0s
Total time	6.41s	6.5s	0.09s

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Reported by octocov