[giri256]

Summary

• replace the unmaintained github.com/tmthrgd/go-hex dependency with the standard library encoding/hex
• remove the dependency from the root module and every nested module
• add focused coverage for empty, single-write, and multi-write hex encoding

Closes #1385

Validation

• gofmt -d internal/hex.go internal/hex_test.go
• go test ./...
• go vet ./...
• compile-only go test -run '^$' in every nested module
• verified the repository contains no remaining tmthrgd/go-hex references

The database-backed driver/pgdriver runtime tests were not run because no local PostgreSQL service was available; their compile-only check passed, and CI supplies the required database services.

[Aoang]

The standard encoding/hex library is very common, so I don't think we need to add unit tests for it. We can remove the internal/hex_test.go file.

[github-actions]

This pull request has been automatically marked as stale because it has not had activity in the last 30 days. If there is no update within the next 7 days, this pr will be closed. Please feel free to give a status update now, ping for review, when it's ready. Thank you for your contributions!