Modernize to Go 1.26

[hayabusa-cloud]

Summary

Bump the minimum Go version to 1.26 and apply go fix modernizers.

Changes

• Bump go.mod directive and CI matrix from 1.25 to 1.26
• Use min()/max() builtins in backoff.go and test helpers
• Use for range N in benchmarks

Test plan

• go test -race passes, 100.0% coverage
• Cross-builds clean (amd64, arm64, riscv64, loong64)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

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[Copilot]

Pull request overview

This PR modernizes the codebase to use Go 1.26 by updating the minimum Go version requirement and applying modern Go syntax patterns introduced in recent versions. The changes leverage built-in min()/max() functions (Go 1.21+) and the for range N syntax (Go 1.22+) to simplify code and improve readability.

Changes:

• Updated Go version requirement from 1.25 to 1.26 in both go.mod and CI configuration
• Replaced conditional min/max logic with built-in min() and max() functions across production and test code
• Modernized benchmark loops to use for range N syntax where loop variables are unused

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
go.mod	Bumped Go directive from 1.25 to 1.26
.github/workflows/ci.yml	Updated CI test matrix to use Go 1.26.x instead of 1.25.x
backoff.go	Replaced conditional min logic with min() builtin in Wait() and Duration() methods
tee_test.go	Simplified test helper Write() method using min() builtin
io_test.go	Modernized multiple test helper Write() methods using min()/max() builtins
bench_test.go	Updated benchmark setup loops to use for range N syntax