Moves formBuilder types, formValidation, useConditionalLogic, useFormSteps,
and formatFieldValue from apps/portal/src to packages/form-schema/src.
Adds @form-schema path alias to both apps/portal and apps/app.
Vue field components remain per-app to allow independent visual evolution.
Behavior-neutral: all 35 Vitest tests green.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Replace monolithic register/[eventSlug].vue with composable field
renderer, conditional-logic engine, stepper, and per-field components
driven by Form Builder schema. Adds flatpickr for date fields.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
