[codex] Add skill reasoning frameworks

[KarmCraft]

Summary

• Add a startup analysis framework for interpreting baseline evidence, confidence, recommendation quality, and edge cases.
• Add a remediation decision framework for classifying targets, choosing reversible actions, shaping approval requests, and stopping on risky cases.
• Add synthetic remediation examples for nonessential tasks, hardware-control services, unknown targets, missing uninstall entries, and disabled residue.
• Update both skill descriptions to name their output artifacts.

Validation

• quick_validate.py sysadmin-windows-startup-performance
• quick_validate.py sysadmin-windows-startup-remediation
• Synthetic startup analyzer fixture run
• Markdown final-newline check
• git diff --check