Context

Part of kcenon/common_system#685 (Wave 1, P0). Code-structure reference: monitoring_system.

Problem (P0, audit-blocking)

• root-level core/ internal/ session/ network-core/ coexist with the canonical src/+libs/ -> code-location SSOT broken
• a 183KB root Makefile provides a second build path alongside CMake

Acceptance Criteria

• sources consolidated under canonical src/+libs/; root duplicate dirs removed or explicitly relocated
• single build system (CMake); Makefile removed or reduced to a thin CMake-delegating wrapper
• package/ top-level dir documented or folded into canonical packaging

Notes

Related to existing #953 (coverage) and #1143 (package version) — coordinate, do not duplicate.

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.