test: guard runner migration quality

[Pluze]

Summary:

• Documented the migration-quality gate that runner migrations must split directly testable non-UI behavior before moving runner bodies.
• Added agent and app-builder guidance against wholesale private-runner moves into +ui/runApp.m.
• Added project debt guardrails for oversized runner debt and DIC/wearable app-owned package migrations requiring direct unit tests for non-UI package functions.

Tests:

• scripts/run_matlab_tests.sh testProject
• scripts/run_matlab_tests.sh checkStyle
• scripts/run_matlab_tests.sh test
• git diff --check

Unverified:

• No app behavior or interactive GUI workflow changed; no manual GUI validation was run.