feat(tasks): linked tasks sync title and subtasks with their note in both directions

Subtasks of a task linked to a note checkbox are tied 1:1 to checkboxes of that note
(subtasks[].blockId), wherever they are moved. ReconcileDocTaskLinks now carries tick, title and
subtasks from the note to the task and adopts new checkboxes directly under the task;
SyncTaskToDoc carries tick, title and subtasks to the note and adds checkboxes for new subtasks.
Deleting is not mirrored. Deepening a task ties its subtasks right away; saves without links keep
the server's links. The sync response reports taskLinks/subtaskLinks; the editor shows an
"Unteraufgabe" badge. v0.36.0.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/storage/docsync.go

@@ -443,43 +443,6 @@ func (s *Store) docTaskLinks(docID string) map[string]string {
 	return links
 }
 
-// ReconcileDocTaskLinks brings tasks linked to blocks in line with the note: a ticked block completes its
-// task, a deleted block unlinks it (the task itself stays). Returns the IDs of changed tasks.
-func (s *Store) ReconcileDocTaskLinks(docID string) []string {
-	links := s.docTaskLinks(docID)
-	if len(links) == 0 {
-		return nil
-	}
-	d, _, err := loadCollabDoc(s.db, docID)
-	if err != nil {
-		return nil
-	}
-	var changed []string
-	for blockID, taskID := range links {
-		b, ok := d.Blocks[blockID]
-		if !ok || b.Deleted {
-			if _, err := s.db.Exec(`UPDATE thoughts SET converted_type = '', converted_ref_id = '' WHERE id = ?`, taskID); err == nil {
-				changed = append(changed, taskID)
-			}
-			continue
-		}
-		kanban := "todo"
-		if b.Props.Checked {
-			kanban = "done"
-		}
-		res, err := s.db.Exec(
-			`UPDATE thoughts SET is_completed = ?, kanban_status = ? WHERE id = ? AND is_completed != ?`,
-			boolInt(b.Props.Checked), kanban, taskID, boolInt(b.Props.Checked))
-		if err == nil {
-			if n, _ := res.RowsAffected(); n > 0 {
-				changed = append(changed, taskID)
-			}
-		}
-	}
-	sort.Strings(changed)
-	return changed
-}
-
 // GetThoughtByIDUnchecked loads a task without access check, for server-internal notifications.
 func (s *Store) GetThoughtByIDUnchecked(thoughtID string) (*domain.Thought, error) {
 	return scanThought(s.db.QueryRow(