test: expand package test coverage and enforce minimum test count

[Copilot]

• Inspect repository structure, package inventory, and existing test coverage
• Run baseline install, lint, build, and test to capture pre-existing failures
• Add or expand tests to ensure each package has at least 5 tests
• Add missing per-package test scripts where needed
• Verify all updated tests pass with workspace test command
• Run build and lint after changes and fix formatting/lint issues
• Run parallel validation on final diff and address valid findings
• Create pull request with summary of changes