fix: persist create-stream form draft to sessionStorage across page reloads (Closes #1087)

[sojetunde8]

Closes #1087

Summary

• Persist multi-step wizard form state to sessionStorage on each change (debounced 500ms) to survive accidental page reloads
• Restore the saved draft on remount with a visible "resumed draft" banner and a "Discard Draft" affordance
• Clear the draft on successful on-chain submission or explicit discard; keep it across normal navigation so the user can return
• Guard recipient deep-link prefill so it doesn't overwrite a restored draft

Testing

• Added unit test suite covering: saving form data on change, restoring draft on mount, banner visibility, discard flow, draft-vs-query-param precedence, and empty-draft edge case
• Verified with existing test patterns and conventions