Extract useMachineCreatePage composable and 5 preview/selector components
from machines/new.vue, reducing it from 1231 to 196 LOC.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Extract assignment normalization utils to shared/utils/assignmentUtils.ts.
Extract selection state management to composables/useMachineCreateSelections.ts.
Extract preview computation and validation to composables/useMachineCreatePreview.ts.
Wire machines/new.vue to use extracted modules (-47% LOC).
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>