Form Module Improvements - Ensure dependent fields refresh/clear on trigger changes

Problem: Fields don’t clear when trigger becomes null/changes.

Actionables:

• Standardize dependency behavior: on change, recompute; on null, clear targets.

• Provide visual indicator when a field is auto-updated.

Success criteria:

• Dependent fields always reflect current trigger state, including nulls.

Context: This proposal is part of the broader storyline AM-I-856.