Add @mention support in AI Chat input (#17943)

## Summary
- Add `@mention` support to the AI Chat text input by replacing the
plain textarea with a minimal Tiptap editor and building a shared
`mention` module with reusable Tiptap extensions (`MentionTag`,
`MentionSuggestion`), search hook (`useMentionSearch`), and suggestion
menu — all shared with the existing BlockNote-based Notes mentions to
avoid code duplication
- Mentions are serialized as
`[[record:objectName:recordId:displayName]]` markdown (the format
already understood by the backend and rendered in chat messages), and
displayed using the existing `RecordLink` chip component for visual
consistency
- Fix images in chat messages overflowing their container by
constraining to `max-width: 100%`
- Fix web_search tool display showing literal `{query}` instead of the
actual query (ICU single-quote escaping issue in Lingui `t` tagged
templates)

## Test plan
- [ ] Open AI Chat, type `@` and verify the suggestion menu appears with
searchable records
- [ ] Select a mention from the dropdown (via click or keyboard
Enter/ArrowUp/Down) and verify the record chip renders inline
- [ ] Send a message containing a mention and verify it appears
correctly in the conversation as a clickable `RecordLink`
- [ ] Verify Enter sends the message when the suggestion menu is closed,
and selects a mention when the menu is open
- [ ] Verify images in AI chat responses are constrained to the
container width
- [ ] Verify the web_search tool step shows the actual search query
(e.g. "Searched the web for Salesforce") instead of `{query}`
- [ ] Verify Notes @mentions still work as before


Made with [Cursor](https://cursor.com)

---------

Co-authored-by: Cursor <cursoragent@cursor.com>

packages/twenty-front/src/modules/activities/components/ActivityRichTextEditor.tsx

@@ -14,7 +14,7 @@ import { isNonTextWritingKey } from '@/ui/utilities/hotkey/utils/isNonTextWritin
 import { Key } from 'ts-key-enum';
 import { useDebouncedCallback } from 'use-debounce';
 
-import { BLOCK_SCHEMA } from '@/activities/blocks/constants/Schema';
+import { BLOCK_SCHEMA } from '@/blocknote-editor/blocks/Schema';
 import { ActivityRichTextEditorChangeOnActivityIdEffect } from '@/activities/components/ActivityRichTextEditorChangeOnActivityIdEffect';
 import { type Attachment } from '@/activities/files/types/Attachment';
 import { type Note } from '@/activities/types/Note';
@@ -27,11 +27,11 @@ import { useIsRecordFieldReadOnly } from '@/object-record/read-only/hooks/useIsR
 import { isTitleCellInEditModeComponentState } from '@/object-record/record-title-cell/states/isTitleCellInEditModeComponentState';
 import { RecordTitleCellContainerType } from '@/object-record/record-title-cell/types/RecordTitleCellContainerType';
 import { getRecordFieldInputInstanceId } from '@/object-record/utils/getRecordFieldInputId';
-import { BlockEditor } from '@/ui/input/editor/components/BlockEditor';
-import { BLOCK_EDITOR_GLOBAL_HOTKEYS_CONFIG } from '@/ui/input/editor/constants/BlockEditorGlobalHotkeysConfig';
-import { useAttachmentSync } from '@/ui/input/editor/hooks/useAttachmentSync';
-import { parseInitialBlocknote } from '@/ui/input/editor/utils/parseInitialBlocknote';
-import { prepareBodyWithSignedUrls } from '@/ui/input/editor/utils/prepareBodyWithSignedUrls';
+import { BlockEditor } from '@/blocknote-editor/components/BlockEditor';
+import { BLOCK_EDITOR_GLOBAL_HOTKEYS_CONFIG } from '@/blocknote-editor/constants/BlockEditorGlobalHotkeysConfig';
+import { useAttachmentSync } from '@/blocknote-editor/hooks/useAttachmentSync';
+import { parseInitialBlocknote } from '@/blocknote-editor/utils/parseInitialBlocknote';
+import { prepareBodyWithSignedUrls } from '@/blocknote-editor/utils/prepareBodyWithSignedUrls';
 import { usePushFocusItemToFocusStack } from '@/ui/utilities/focus/hooks/usePushFocusItemToFocusStack';
 import { useRemoveFocusItemFromFocusStackById } from '@/ui/utilities/focus/hooks/useRemoveFocusItemFromFocusStackById';
 import { FocusComponentType } from '@/ui/utilities/focus/types/FocusComponentType';