[task] Optimize SC2002 useless cat patterns in analysis workflows

[github-actions]

Objective

Optimize cat file | command patterns to more efficient command < file syntax in three analysis workflows.

Context

Static analysis identified 3 instances of SC2002 ("Useless cat. Consider 'cmd < file | ..' or 'cmd file | ..' instead"). While not a security issue, this is a code style improvement that can reduce unnecessary process overhead.

Related to discussion #3527.

Approach

1. Review the following workflows:
   • copilot-agent-analysis
   • copilot-pr-prompt-analysis
   • prompt-clustering-analysis
2. Locate cat file | command patterns
3. Replace with more efficient alternatives:
   • command < file (if command reads from stdin)
   • command file (if command accepts file argument)
4. Verify commands still work with new syntax

Files to Modify

• .github/workflows/copilot-agent-analysis.md
• .github/workflows/copilot-pr-prompt-analysis.md
• .github/workflows/prompt-clustering-analysis.md

Acceptance Criteria

• All useless cat patterns replaced with efficient alternatives
• Run gh aw compile --actionlint on each workflow shows no SC2002 warnings
• Workflows compile successfully
• Functionality preserved (verify with test runs if possible)

Impact

Eliminates 3 code style warnings and slightly improves workflow efficiency.
Related to #3527

AI generated by Plan Command for discussion #3527