[dasc] Title Not Editable in Structured Content Editor

## Structured Content Title Not Editable in Structured Content Editor

### Current Behavior:
The Structured Content title cannot be authored or modified directly within the Structured Content Editor. At present, users must open the DA Editor and manually edit the da-form block title to make changes.

### Expected Behavior:
The Structured Content title should be editable directly within the Structured Content Editor, without requiring access to the DA Editor.

Start in the Structured Content Editor entry point and reproduce the title-authoring flow described in the issue; use the DA Editor and its da-form block title as the current comparison. Done means users can edit the Structured Content title directly in the Structured Content Editor without opening the DA Editor, with the change reflected in the saved content.

Written by the indexing model from the issue text.