refactor(code-review): clean up step-01 substep 3 and add error handling

Substep 3 (Extract File List):
- Removed repetitive wording
- Reference {story_content} variable instead of generic "story file"
- Add error handling: if Dev Agent Record/File List not found, set story_file_list = NO_FILE_LIST
- Consistent with NO_GIT pattern used elsewhere

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

src/modules/bmm/workflows/4-implementation/code-review/steps/step-01-load-story.md

@@ -56,9 +56,9 @@ Verify the filename ends with `.md` extension. Remove `.md` to get `story_key` (
 
 ### 3. Extract File List from Story
 
-Extract `story_file_list` from the Dev Agent Record → File List section of the story file.
+Extract `story_file_list` from the Dev Agent Record → File List section of {story_content}.
 
-Set `story_file_list` = list of files from Dev Agent Record → File List
+**If Dev Agent Record or File List section not found:** Report to user and set `story_file_list` = NO_FILE_LIST.
 
 ### 4. Discover Git Changes