Intrinsic callback naming

Contract

v0.1.12 renames interactive callback attributes to match HTML/DOM event names as closely as Go syntax allows. GX uses on-prefixed camel-case names:

Browser event GX attribute Go props field
click onClick OnClick
submit onSubmit OnSubmit
input onInput OnInput
change onChange OnChange

The old bare callback spellings are removed, not kept as aliases. GX is a new framework, so public examples, lint diagnostics, compiler lowering, generated Go, runtime wiring, and test fixtures should use only the on* names.

package notesui

import "github.com/busdk/bus-gx/pkg/gx"

func NoteEditor(title string, setTitle func(string), save func()) gx.Node {
  return (
    <form onSubmit={save}>
      <label for="title"><Text value={"Title"}></Text></label>
      <input id="title" name="title" value={title} onInput={setTitle} />
      <button type="submit"><Text value={"Save"}></Text></button>
    </form>
  )
}

Lowercase intrinsic elements store callback functions in Props with the same attribute name, such as onClick or onInput. Uppercase component calls map the same attribute names to Go fields such as OnClick or OnInput.

Boundary

This patch changes names only. It does not add new event payload types, effect hooks, state hooks, expanded intrinsic elements, or resource helpers.