Add riscv64 nightly LKL build to GitHub Action

[rota1001]

Previously, the GitHub Actions only build LKL of x86_64 and aarch64 architectures. This adds the riscv64 support by using the RISE GitHub App to do the compilation.

This GitHub Action is tested[1] on my repo, and it runs successfully.

Also, it is found that the GitHub Action has not been run for a long time because the script will compare the hash of commit between the upstream LKL and the last release. Because of this, the release format has been wrong from Commit f08907f but not being found. This also fixs it.

Also because of this, before the new GitHub Action is run, the old release must be removed because the upstream LKL commit doesn't change.

[1] https://github.com/rota1001/kbox/actions/runs/24160395840

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Summary by cubic

Add riscv64 to the nightly LKL GitHub Action and fix tarball packaging so releases are consistent and include all three architectures.

• New Features

  • Build riscv64 nightly via the RISE GitHub App on ubuntu-24.04-riscv; publish liblkl-riscv64.tar.gz.
  • Correct tar packaging (-C ... .) and update release notes to list x86_64, aarch64, and riscv64.
  • Increase build timeout to 360 minutes and add riscv64 detection in scripts/common.sh.

• Migration

  • Delete the existing lkl-nightly release before running the workflow if the upstream LKL commit hasn’t changed, or the commit comparison may prevent a new run.

^{Written for commit 0000e3e. Summary will update on new commits.}

[cubic-dev-ai]

No issues found across 2 files

[jserv]

Thank @rota1001 for contributing!