ux(ui): readable persona form instead of raw JSON + step-by-step guides for non-IT users

- GroupEdit: replace raw JSON persona dump with a labeled, sectioned PersonaForm
  (ข้อมูลพื้นฐาน / ข้อมูลลูกค้า / การขาย / ช่องทาง) shown in a modal; admin edits by field.
- New reusable components/PersonaForm.vue.
- GroupBuilder + Personas: add friendly step-by-step guidance cards ('วิธีสร้าง',
  'วิธีฝึก') so admins/trainees know what to do at each step.
- Rebuild dist.

frontend/dist/assets/GroupBuilder-B8gqmNUJ.css

@@ -0,0 +1 @@
+.guide[data-v-c7f3b0ac]{background:#eef2ff;border-color:#c7d2fe;margin-bottom:16px}.req[data-v-c7f3b0ac]{color:var(--red)}