Fix OpenROM-bins Cloning, Remove Stale Commit Pin & Fix Working Directory Traversal

[ClausValcaTD]

This PR addresses two issues with fetching OpenROM-bins:

1. Removes hardcoded obsolete commit hash 586f7cc54df0facf9df9d3066c70e6b434b93753 from .github/workflows/Release.yml and .github/workflows/Flatpak.yml, allowing the latest OpenROM-bins from main (including checksums.sha256 and NKit 3.1.0 binaries) to be cloned.
2. Fixes working directory traversal during checksum verification by using subshells (cd bins && ...) in workflows and pushd bins / popd in build_windows.bat, ensuring downstream copy commands correctly resolve paths relative to the repository root.

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PR created automatically by Jules for task 14752942830787187812 started by @ClausValcaTD

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