fix: add missing Qwen support to release workflow and agent scripts

- Add Qwen template assets to release workflow for proper distribution
- Include qwen case in bash/powershell agent context update scripts
- Fix missing spec-kit-template-qwen-sh/ps release assets issue
- Ensure Qwen support consistency across all tooling components

Resolves critical release problem where Qwen templates were generated
but not included in GitHub releases, causing initialization failures.