fix(explore-auto): correct intermediate file structure references

Fix file structure documentation to reflect actual implementation:
- user_selection is embedded in analysis-options.json, not separate file
- computed-styles.json only exists in URL mode
- dom-structure-*.json only exists in URL mode
- Remove obsolete design-space-analysis.json reference

Updated:
- .intermediates/style-analysis/: analysis-options.json (with embedded user_selection), computed-styles.json (URL mode)
- .intermediates/layout-analysis/: analysis-options.json (with embedded user_selection), dom-structure-*.json (URL mode)

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

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

.claude/commands/workflow/ui-design/explore-auto.md

@@ -581,8 +581,8 @@ Design Quality:
 
 📂 {base_path}/
   ├── .intermediates/          (Intermediate analysis files)
-  │   ├── style-analysis/      (computed-styles.json, design-space-analysis.json)
-  │   └── layout-analysis/     (analysis-options.json, user-selection.json, dom-structure-*.json)
+  │   ├── style-analysis/      (analysis-options.json with embedded user_selection, computed-styles.json if URL mode)
+  │   └── layout-analysis/     (analysis-options.json with embedded user_selection, dom-structure-*.json if URL mode)
   ├── style-extraction/        ({s} complete design systems)
   ├── layout-extraction/       ({n×l} layout template files: layout-{target}-{variant}.json)
   ├── prototypes/              ({total} assembled prototypes)