fix: run Transformer release step in Bash

[wimi321]

Summary

• run both standard and NVIDIA Transformer bundle steps under Bash on every runner
• prevent PowerShell from parsing Bash line continuations as invalid unary operators
• lock the shell contract in release tests

Verification

• pnpm test (262/262)
• pnpm typecheck
• pnpm build
• exact Windows standard and NVIDIA release failure reproduced from run 33046549107

No incomplete v0.4.21 Release was published.