feat: Enhance navigation and cleanup for graph explorer view

- Added a cleanup function to reset the state when navigating away from the graph explorer.
- Updated navigation logic to call the cleanup function before switching views.
- Improved internationalization by adding new translations for graph-related terms.
- Adjusted icon sizes for better UI consistency in the graph explorer.
- Implemented impact analysis button functionality in the graph explorer.
- Refactored CLI tool configuration to use updated model names.
- Enhanced CLI executor to handle prompts correctly for codex commands.
- Introduced code relationship storage for better visualization in the index tree.
- Added support for parsing Markdown and plain text files in the symbol parser.
- Updated tests to reflect changes in language detection logic.

codex-lens/src/codexlens/config.py

@@ -66,6 +66,8 @@ class Config:
             "go": {"extensions": [".go"], "tree_sitter_language": "go"},
             "zig": {"extensions": [".zig"], "tree_sitter_language": "zig"},
             "objective-c": {"extensions": [".m", ".mm"], "tree_sitter_language": "objc"},
+            "markdown": {"extensions": [".md", ".mdx"], "tree_sitter_language": None},
+            "text": {"extensions": [".txt"], "tree_sitter_language": None},
         }
     )
     parsing_rules: Dict[str, Dict[str, Any]] = field(