Context

Part of kcenon/common_system#685 (Wave 2, P1).

Acceptance Criteria

• add root VERSIONING.md (single version-policy SSOT)
• dedup docs/ vs docs/advanced/ ARCHITECTURE/API_REFERENCE/CHANGELOG/PERFORMANCE
• README.kr.md raised to >= 70% of README.md
• confirm sunset schedule for deprecated forward shims
• remove stray root files (ANALYSIS_README.md, README_KO_UPDATE_NOTES.md)

Derived from the 2026-05-30 multi-agent cross-system level-matching analysis (workflow wf_0a968699-e07). Reference systems: documentation=common_system, code-structure=monitoring_system, tests/examples=container_system.