feat: enable Rich Text as a creatable field type (#18634)

## Summary

- Removes `RICH_TEXT` from the excluded/hidden field types in the
settings UI so users can create rich text fields on any object (not just
Note/Task)
- Creates a generic `RichTextFieldEditor` component that uses standard
`useUpdateOneRecord` for persistence, decoupled from the
Note/Task-specific `ActivityRichTextEditor`
- Updates the inline `RichTextFieldInput` and side panel to route to the
appropriate editor based on object type (activity editor for Note/Task,
generic editor for everything else)

## Details

### Tier 1 — Settings UI unlock
- Removed `RICH_TEXT` from `excludedFieldTypes` in
`SettingsObjectNewFieldSelect.tsx`
- Removed `RICH_TEXT` from `SettingsExcludedFieldType` type union
- Added `RICH_TEXT` to `previewableTypes` in
`SettingsDataModelFieldSettingsFormCard`

### Tier 2 — Generic inline editing
- New `RichTextFieldEditor` — a generic BlockNote editor that works for
any object using `useUpdateOneRecord` (no activity-specific coupling)
- `RichTextFieldInput` now branches: `ActivityRichTextEditor` for
Note/Task, `RichTextFieldEditor` for all other objects
- Generalized side panel state (`viewableRichTextComponentState`) from
`activityId`/`activityObjectNameSingular` to
`recordId`/`objectNameSingular`/`fieldName`
- `useOpenRichTextInSidePanel` now accepts an optional `fieldName`
parameter

### Tier 3 — Verification
- Search: only `markdown` subfield is indexed (correct behavior)
- Filters: `RichTextFilter` GraphQL input type already exists
- Import/export: `markdown` subfield is already marked `isImportable:
true`

packages/twenty-front/src/modules/settings/data-model/fields/forms/components/SettingsDataModelFieldSettingsFormCard.tsx

@@ -202,6 +202,7 @@ const previewableTypes = [
   FieldMetadataType.RAW_JSON,
   FieldMetadataType.RELATION,
   FieldMetadataType.MORPH_RELATION,
+  FieldMetadataType.RICH_TEXT,
   FieldMetadataType.SELECT,
   FieldMetadataType.TEXT,
   FieldMetadataType.UUID,

packages/twenty-front/src/modules/settings/data-model/types/SettingsExcludedFieldType.ts

@@ -3,5 +3,5 @@ import { type PickLiteral } from '~/types/PickLiteral';
 
 export type SettingsExcludedFieldType = PickLiteral<
   FieldType,
-  'POSITION' | 'TS_VECTOR' | 'RICH_TEXT' | 'NUMERIC'
+  'POSITION' | 'TS_VECTOR' | 'NUMERIC'
 >;