Add regression-test requirements to stabilization bug fixes

[alx-so]

Problem

The known stabilization bugs should not be fixed without regression coverage. Each fix should either add a focused test in the same PR or explicitly document why the behavior cannot be covered with the current test harness.

This issue is the testing gate for the existing stabilization bug issues.

Related bug issues

• Search results use stale item data after items prop changes #3 Search results use stale item data after items prop changes
• Multiple mode can pass string arrays to TextInput value #4 Multiple mode can pass string arrays to TextInput value
• Select and InputSelect ignore controlled value prop updates #5 Select and InputSelect ignore controlled value prop updates
• Freeform and default tags can receive duplicate IDs #6 Freeform and default tags can receive duplicate IDs
• Build config excludes wrong example folder and test suite has no coverage #7 Build config excludes wrong example folder and test suite has no coverage
• Wire or remove declared public props that are currently no-op #8 Wire or remove declared public props that are currently no-op

Acceptance criteria

• Each bug-fix PR for Search results use stale item data after items prop changes #3 through Wire or remove declared public props that are currently no-op #8 includes regression coverage where practical.
• Tests are added before or alongside the production fix, not after release.
• If a regression test would currently fail before the fix, it is introduced in the same PR as the fix so CI remains green.
• Any bug that cannot be covered by the current harness links to a follow-up testing task with a clear reason.
• The final stabilization milestone has meaningful coverage for search, controlled state, multi-select tags, and public prop behavior.