feat: Add install apk on riscv64 arch tests

[hustcer]

feat: Add install apk on riscv64 arch tests

[github-actions]

Script Analysis

• New GitHub Actions workflow for testing Nu APK package installation on RISC-V (Alpine Linux)
• Uses QEMU emulation for RISC-V architecture testing
• Tests against multiple Alpine Linux versions (latest and 3.20)
• Adds untrusted package repository (Gemfury) due to unsigned packages
• Verifies installation by checking installed shell and running basic Nu commands

Security Review

• ❗ Potential security risk using --allow-untrusted flag with apk (line 196) - packages aren't verified
• ⚠️ Adds external repository (alpine.fury.io) without signature verification
• Note: This appears to be temporary testing configuration rather than production deployment

Optimization Suggestions

• Consider adding package verification step if/when packages become signed
• Could add cleanup step to remove the repository after testing
• Might want to validate the installed Nu version against expected version

Overall Quality: 4
(Good for testing purposes, but would need additional security measures for production use)