Fix false-green audits and test mixed workspaces

[tugrakaymakcioglu]

TimmyTest could report green results from generated assert True stubs, ignore a failing Gradle process after parsing a passing case, select only one related test for a changed module, and execute only one ecosystem in a mixed repository. Plain Dart packages with a web/ folder could also be routed to flutter test.

This change marks generated Python/Node/Go/Rust stubs as skipped placeholders that cannot raise readiness, rejects comment-only and old trivial Python stubs as test evidence, treats nonzero process exits as CI failures, runs each configured root or nested workspace, selects every related test (with full-suite fallback when mapping is uncertain), uses pubspec contents for Flutter detection, and keeps same-named low-coverage files from distinct directories. It includes the previously uncommitted Dart/Flutter runner improvements from the local checkout while preserving that checkout unchanged.

Validation: 250 tests passed locally; Ruff and mypy passed; wheel builds. The readiness score remains a heuristic association score, not a guarantee of behavioral coverage across every language or architecture.