feat(modal): implement multi-step (steps) mechanism

[uttam12331]

Summary

Implements the multi-step modal feature from #276. A new steps prop splits a modal into sequential pages with Next/Back navigation and animated transitions, while leaving classic elements based modals unchanged.

<Modal
  title="Register"
  theme="Crimson"
  steps={[
    { title: 'Account Details', elements: [{ type: 'text', name: 'firstName', placeholder: 'First Name', amount: 1 }] },
    { title: 'Security', elements: [{ type: 'password', name: 'password', placeholder: 'Password', amount: 1 }] }
  ]}
  onSubmit={(data) => console.log(data)}
/>

What it does

• Per-step rendering — only the current step's elements are shown, reusing the existing field-rendering block and SerializeData pipeline (each step is serialized through the same path).
• Navigation — Next/Back buttons replace the default submit button; Next becomes the submit action on the final step. Back is hidden on the first step.
• Per-step validation — handleValidation runs against the active step before allowing Next; the final submit re-validates every step so a back-navigated/skipped step can't slip through.
• State persistence — data and errors live in shared state and persist across steps (fields are initialised once across all steps, so navigation never resets input).
• Animated transitions — GSAP slide/fade between steps, plus a progress-dot indicator and per-step titles.
• Backwards compatible — existing elements modals are untouched; the field wrapper uses display: contents when not stepped, so layout is identical to before.

Testing

• Added a two-step registration example to the devbench (devbench/src/component/modal.jsx), toggleable via useSteps.
• npm run build -w devbench succeeds (96 modules transformed).
• Prettier-clean; no new lint errors introduced.

Closes #276

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[younisdev]

Hey @uttam12331, great work on this! I'll get to reviewing it soon! Just been a bit busy. Thanks for your patience!