docs: Update all references from old 05-Plot/06-First Draft to merged 05-First Draft

- Update project_template test to verify old directories are NOT created
- Update hover text and comments in project.rs
- Update comments and code in file_list.rs
- Update comment in spelling.rs
- Add test assertions to verify 05-Plot and 06-First Draft don't exist in new projects

This ensures all code references match the merged directory structure where
planning and draft content are combined in 05-First Draft with YAML frontmatter.

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

src/app/file_list.rs

@@ -10,14 +10,14 @@ const MAX_DISPLAY_NAME_LEN: usize = 30;
 /// Convert a manuscript folder path to its corresponding outline file path.
 ///
 /// For the snowflake template:
-/// - `06-First Draft/Act 1` → `04-Outline/scene_breakdown/act_01.md`
-/// - `06-First Draft/Act 2` → `04-Outline/scene_breakdown/act_02.md`
+/// - `05-First Draft/Act 1` → `04-Outline/scene_breakdown/act_01.md`
+/// - `05-First Draft/Act 2` → `04-Outline/scene_breakdown/act_02.md`
 /// - etc.
 fn outline_path_for_folder(folder_path: &str) -> Option<String> {
     // Split the path into components
     let parts: Vec<&str> = folder_path.split('/').collect();
     
-    // We expect paths like "06-First Draft/Act 1"
+    // We expect paths like "05-First Draft/Act 1"
     if parts.len() < 2 {
         return None;
     }
@@ -542,8 +542,7 @@ impl App {
                     if ui
                         .button("＋ New Scene")
                         .on_hover_text(
-                            "Create a planning file in 05-Plot and a linked draft file \
-                             in 06-First Draft with automatic cross-references",
+                            "Create a new scene file with YAML frontmatter in 05-First Draft"
                         )
                         .clicked()
                     {