feat(parser): add Elixir language support

- [x] Add Elixir documentation extraction (@doc and @moduledoc attributes)
- [x] Add Elixir symbol extraction (modules, functions, macros, structs, protocols)
- [x] Add tree-sitter Elixir language parser integration
- [x] Add Elixir language detection for .ex and .exs file extensions
- [x] Add Elixir symbol extraction tests
- [x] Update language support table in README
- [x] Improve install script with package manager detection and LSP installation
- [x] Fix shell script portability (replace echo -e with printf)
- [x] Fix checksum verification in install script for macOS/Linux compatibility

pkg/protocol/types.go

@@ -60,6 +60,7 @@ const (
 	LangVue        Language = "vue"
 	LangJSON       Language = "json"
 	LangYAML       Language = "yaml"
+	LangElixir     Language = "elixir"
 	LangUnknown    Language = "unknown"
 )
 
@@ -87,6 +88,8 @@ func DetectLanguage(filename string) Language {
 		return LangJSON
 	case ".yaml", ".yml":
 		return LangYAML
+	case ".ex", ".exs":
+		return LangElixir
 	default:
 		return LangUnknown
 	}