feat: Ensure 06-First Draft folder is expanded in file list when opening projects

- Add explicit code in open_workspace to ensure manuscript folder is not collapsed
- Update README to clarify that project root is opened with manuscript folder expanded
- Keep workspace at project root but ensure file list shows 06-First Draft expanded

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

README.md

@@ -503,12 +503,11 @@ to the template as the `project_name`, `author` and `description` variables.
 Nothing is written until you press **Create**; generation runs in the background,
 so a template whose hooks talk to the network doesn't freeze the editor.
 
-When it finishes, the app opens the project's **`06-First Draft`** subfolder as
-the workspace — that is where the snowflake template keeps the chapter files, in
-`Act 1/`, `Act 2/` and `Act 3/` subfolders that the
-[folder tree](#organising-with-folders) shows directly. If the template didn't
-produce that folder, the project root is opened instead and the status bar says
-so.
+When it finishes, the app opens the project root as the workspace,
+with the **`06-First Draft`** folder (where the snowflake template keeps the
+chapter files in `Act 1/`, `Act 2/` and `Act 3/` subfolders) automatically
+expanded in the file list. If the template didn't produce that folder, the
+status bar notes that nothing is marked as the manuscript.
 
 A folder only appears in the file panel once it holds a `.md` file — the
 template's empty acts are held open with `.gitkeep`, which is not markdown, so