fix: createForm missing onboard override and SelfClosingElement type

- Add onboard() to createForm that batch-wraps register(), preventing
  bulk field registration from bypassing form-specific setup (validation
  state, Object.defineProperty value wrapping, pristine tracking)
- Fix SelfClosingElement type: keyof typeof array gives numeric indices,
  (typeof array)[number] gives the correct string union of tag names

Author: johnleider

packages/0/src/composables/createForm/index.ts

@@ -260,9 +260,14 @@ export function createForm<
     return ticket
   }
 
+  function onboard (registrations: Partial<Z>[]): E[] {
+    return registry.batch(() => registrations.map(r => register(r)))
+  }
+
   return {
     ...registry,
     register,
+    onboard,
     reset,
     submit,
     validateOn,

packages/0/src/constants/htmlElements.ts

@@ -98,4 +98,4 @@ export type HTMLElementName = keyof HTMLElementTagNameMap
 /**
  * Type for self-closing HTML elements
  */
-export type SelfClosingElement = keyof typeof selfClosingTags
+export type SelfClosingElement = (typeof selfClosingTags)[number]