feat(fullstack): Replace TITLE_BODY element with rich text editor

CLAUDE.md

@@ -99,7 +99,7 @@ Application Form
             └── Form Elements (FormElement)
                  ├── id (UUID - generated by backend)
                  ├── reference (string - custom key like "art_der_massnahme")
-                 ├── type (SELECT, CHECKBOX, RADIOBUTTON, TEXTFIELD, TEXTAREA, SWITCH, TITLE_BODY_TEXTFIELDS, DATE)
+                 ├── type (SELECT, CHECKBOX, RADIOBUTTON, TEXTFIELD, TEXTAREA, SWITCH, RICH_TEXT, DATE)
                  ├── title, description
                  ├── options (FormOption[])
                  │    ├── value, label
@@ -743,7 +743,7 @@ act -n
      - `GET /application-forms/{id}/html`
      - `GET /application-forms/{id}/pdf`
    - Verify these render correctly (with saved values):
-     - `TEXTFIELD`, `TEXTAREA`, `DATE`, `TITLE_BODY_TEXTFIELDS`
+     - `TEXTFIELD`, `TEXTAREA`, `DATE`, `RICH_TEXT`
      - `SELECT`, `RADIOBUTTON`, `CHECKBOX`, `SWITCH`
    - If you changed backend filtering or templating, ensure:
      - Template sections (`isTemplate=true`) remain excluded from export
@@ -757,6 +757,9 @@ act -n
 11. **Clean Code: order functions by abstraction (top-down, like a book)**
    - Put the highest-level, most readable entry points first (public API / primary flows), then progressively lower-level helpers below.
    - Keep functions at the same level of abstraction grouped together; details should live “later” (below) so the file reads top-to-bottom without jumping around.
+12. **No hardcoded UI strings** (i18n)
+   - Never hardcode user-facing text in Vue components/composables.
+   - Always add UI strings to `legalconsenthub/i18n/locales/de.json` and `legalconsenthub/i18n/locales/en.json` and reference them via `$t()` / `useI18n()`.
 
 ---