feat(core): drop doc onto split view (#9487)

fix AF-2068, AF-2069, AF-1175, AF-2061, AF-2079, AF-2034, AF-2080, AF-1960, AF-2081

1. replace `dnd-kit` with `@atlaskit/pragmatic-drag-and-drop`
2. allow creating split views by drag & drop the following
   a. WorkbenchLinks (route links), like journals, trash, all docs
   b. doc refs
   c. tags/collection
3. style adjustments to split view
4. remove split view's feature flag and make it GA for electron

https://github.com/user-attachments/assets/6a3e4a25-faa2-4215-8eb0-983f44db6e8c

packages/frontend/core/src/components/blocksuite/block-suite-editor/journal-doc-title.tsx

@@ -23,7 +23,9 @@ export const BlocksuiteEditorJournalDocTitle = ({ page }: { page: Blocks }) => {
     <div className="doc-title-container" data-testid="journal-title">
       <span data-testid="date">{localizedJournalDate}</span>
       {isTodayJournal ? (
-        <span className={styles.titleTodayTag}>{t['com.affine.today']()}</span>
+        <span className={styles.titleTodayTag} data-testid="date-today-label">
+          {t['com.affine.today']()}
+        </span>
       ) : (
         <span className={styles.titleDayTag}>{day}</span>
       )}

packages/frontend/core/src/components/blocksuite/block-suite-header/journal/today-button.tsx

@@ -8,7 +8,9 @@ export const JournalTodayButton = () => {
   const journalHelper = useJournalRouteHelper();
 
   const onToday = useCallback(() => {
-    journalHelper.openToday();
+    journalHelper.openToday({
+      replaceHistory: true,
+    });
   }, [journalHelper]);
 
   return (