fix(golden): preserve line endings across platforms

[alloutflo]

• I have read CONTRIBUTING.md.
• I have created a discussion that was approved by a maintainer (for new features). Not applicable: this is a bug fix for ci: fix exp/teatest tests on windows #389.

What changed

• mark *.golden files as binary so Git preserves their bytes on every platform
• remove the Windows-only CRLF normalization workaround from exp/golden

Why

Git for Windows can otherwise rewrite golden fixtures during checkout. Keeping those fixtures byte-for-byte stable fixes the cross-platform behavior at the source instead of normalizing only the expected value at test runtime.

Verification

• go build ./..., go test -race ./..., and go vet ./... in exp/golden
• go build ./..., go test -race ./..., and go vet ./... in exp/teatest
• go build ./..., go test -race ./..., and go vet ./... in exp/teatest/v2
• checkout simulation with core.autocrlf=true: the golden fixture retained zero CRLF sequences and the same SHA-256 digest as the source file

Fixes #389.

Development assistance: OpenAI Codex (GPT-5).