refactor: deepen modules, consolidate inference, delete dead code

- Extract build_graph/load_config/create_renderer in presentation (393→~250 lines)
- Move module inference into ModuleName::from_path(), delete 3 scattered copies
- Move resolve_relationships/filter_external_imports into CodeGraph
- Add LanguageExtractor trait in tree-sitter adapter
- Add CodeGraph::elements_by_module(), replace 6 identical grouping loops
- Delete dead RenderDiagrams query

crates/adapters/tree-sitter/src/python/mod.rs

@@ -7,6 +7,16 @@ use archlens_domain::{
     Relationship, RelationshipKind,
 };
 
+use crate::language_extractor::LanguageExtractor;
+
+pub struct PythonExtractor;
+
+impl LanguageExtractor for PythonExtractor {
+    fn analyze(&self, source: &str, file_path: &FilePath) -> Result<AnalysisResult, DomainError> {
+        analyze(source, file_path)
+    }
+}
+
 pub fn analyze(source: &str, file_path: &FilePath) -> Result<AnalysisResult, DomainError> {
     let mut parser = Parser::new();
     parser