feat: implement FieldRichTextEditor component using TipTap and Mantine integration

packages/ui/docs/FORM-COMPONENTS.md

@@ -122,7 +122,8 @@ packages/ui/src/components/Form/
     ├── tags-input.field.tsx           # FieldTagsInput
     ├── chip-group.field.tsx           # FieldChipGroup
     ├── segmented-control.field.tsx    # FieldSegmentedControl
-    └── file-input.field.tsx           # FieldFileInput
+    ├── file-input.field.tsx           # FieldFileInput
+    └── rich-text.field.tsx            # FieldRichTextEditor
 ```
 
 Each field file is a thin one-liner:
@@ -889,7 +890,11 @@ export const FieldDatePicker = withRHF<DatePickerInputProps>(
 | `FieldColorPicker` | `ColorPicker` | Color | Color picker only (uses `Input.Wrapper`) |
 | `FieldLocalSelect` | `Select / MultiSelect` | Selection | Stores full `T` or `T[]` object in RHF instead of string ID. Accepts static `options` array with `valueKey`/`labelKey` mapping. |
 | `FieldAsyncSelect` | `Select / MultiSelect` | Selection | Async paginated object select with IoC `loadOptions` callback. Supports search-keyed caching, `defaultOptions` for edit forms, and automatic pagination detection. |
-| `FieldFileInput` | `FileInput` | File | File upload input |
+| `FieldFileInput` | `<FileInput />` | `File | File[] | null` |
+| `FieldRichTextEditor` | `@mantine/tiptap` | `string` (HTML) |
+
+### Rich Text Editor (TipTap)
+The `FieldRichTextEditor` component integrates `@mantine/tiptap` directly with React Hook Form. It safely stores the Editor's HTML output directly into the RHF state as a `string`. Because TipTap is an uncontrolled editor natively, this field uses a specialized `useController` wrapper that automatically syncs bidirectional updates (e.g., calling `editor.commands.setContent(field.value)` when the form is reset or async default values arrive).
 
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