ci: Fix Windows release attestation by writing CRLF checksums

[beekld]

Summary

Windows release jobs fail at actions/attest: its parser splits checksums.txt on os.EOL ('\r\n' on Windows), but the Generate-checksums step writes LF-only. The whole file becomes a single record whose subject name exceeds 256 chars.

Pipe through sed 's/$/\r/' on the Windows branch to produce CRLF. Linux and macOS unchanged.

Confirmed on a Windows runner: sha256sum on Git Bash writes LF only, the base64 round-trip preserves it, and Node os.EOL on the runner is "\r\n".

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Note

Low Risk
CI-only line-ending tweak on the Windows checksum branch; no runtime SDK or security logic changes.

Overview
Fixes Windows release jobs failing at actions/attest when parsing checksums.txt.

On the Windows matrix leg, the Generate checksums file step now pipes decoded hashes through sed 's/$/\r/' so each line ends with CRLF, matching how actions/attest splits on os.EOL (\r\n) on Windows. LF-only output was treated as one record and blew past subject name limits. Linux and macOS checksum generation is unchanged.

The same one-line change is applied everywhere that Windows hash output is written: manual-sdk-release-artifacts.yml and four release jobs in release-please.yml (client, server, redis, dynamodb).

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