Form Module Improvements - Custom dimensions on all field types (e.g., Personnel Picker)

Problem: Some fields overflow compact layouts.

Actionables:

• Add width presets (S/M/L/Full) and custom width (%) per field.

• Allow max-height for dropdown/pickers with scroll.

• Provide grid guidelines in builder.

Success criteria:

• Fields respect assigned dimensions without overlapping; preview reflects runtime.

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