Expand recipe form with metadata fields

[dgee2]

Goal

Expand the recipe creation/edit form to include all recipe metadata fields.

Spec reference

docs/specs/recipe-creation-target-architecture.md — §"Frontend target architecture – Recipe editor"

Implementation notes

• Add to new-recipe-form.vue (or extract a shared recipe-form.vue):
  • Summary textarea
  • Servings number input
  • Yield text input
  • Prep time, cook time, total time number inputs (minutes)
• Create or reuse reusable generic form components (text-field, number-field) in src/components/generic/form/ with co-located Storybook stories
• Frontend validation: Title is required

Acceptance criteria

• All metadata fields render in the form
• Required validation prevents submit when title is empty
• Storybook story for each new generic field component

Testing

• Vitest: form validation (empty title blocked, valid form submits)
• Vitest: each new generic component renders correctly

Part of#1100