XY-692: Retire migrated Radar Python scripts and make decodex radar the documented path

[yvette-carlisle]

Summary

• Remove migrated deterministic Radar Python entrypoints and legacy script tests now covered by decodex radar ....
• Route Makefile content validation through decodex radar validate.
• Update active docs, runbooks, release-delta examples, and repo-local skills to make the Rust CLI the documented operator path while keeping run_codex_analysis.py as the AI helper boundary.

Validation

• cargo make fmt
• cargo make lint-fix
• cargo make test
• cargo make decodex-checks
• cargo make check
• Focused semantic drift audit and active-reference search for retired Python paths.