docs: converge governance guidance

[Pluze]

Summary

• Make docs/testing.md the single source for validation commands; README, scoped AGENTS, and skills now route to it.
• Add docs/architecture.md temporary debt inventory for DIC/wearable private helpers and electrochem +core/dispatch.m routers.
• Add project guardrails for human-doc workflow leakage, duplicate build-task matrices, private-helper debt growth, Workflow adapters, and +core dispatch scope growth.

Tests

• rg static drift scans for buildtool matrix, agent-only human-doc leakage, and debt keywords
• git diff --check
• scripts/run_matlab_tests.sh testProject
• scripts/run_matlab_tests.sh checkStyle
• scripts/run_matlab_tests.sh checkProject
• scripts/run_matlab_tests.sh test

Unverified

• Interactive GUI workflows not run; this change is docs and static guardrails only.

Follow-up

• Remove the documented DIC/wearable private-helper and electrochem dispatch debt in later app migration PRs.