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/language_extractor.rs

@@ -0,0 +1,5 @@
+use archlens_domain::{AnalysisResult, DomainError, FilePath};
+
+pub trait LanguageExtractor {
+    fn analyze(&self, source: &str, file_path: &FilePath) -> Result<AnalysisResult, DomainError>;
+}

crates/adapters/tree-sitter/src/lib.rs

@@ -1,3 +1,4 @@
+mod language_extractor;
 mod python;
 mod rust;
 mod tree_sitter_analyzer;

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

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

@@ -42,6 +42,16 @@ use archlens_domain::{
     Relationship, RelationshipKind, Visibility,
 };
 
+use crate::language_extractor::LanguageExtractor;
+
+pub struct RustExtractor;
+
+impl LanguageExtractor for RustExtractor {
+    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

crates/adapters/tree-sitter/src/tree_sitter_analyzer.rs

@@ -1,8 +1,13 @@
 use archlens_domain::{AnalysisResult, DomainError, Language, SourceFile, ports::SourceAnalyzer};
 
-use crate::{python, rust};
+use crate::language_extractor::LanguageExtractor;
+use crate::python::PythonExtractor;
+use crate::rust::RustExtractor;
 
-pub struct TreeSitterAnalyzer;
+pub struct TreeSitterAnalyzer {
+    rust: RustExtractor,
+    python: PythonExtractor,
+}
 
 impl Default for TreeSitterAnalyzer {
     fn default() -> Self {
@@ -12,7 +17,18 @@ impl Default for TreeSitterAnalyzer {
 
 impl TreeSitterAnalyzer {
     pub fn new() -> Self {
-        Self
+        Self {
+            rust: RustExtractor,
+            python: PythonExtractor,
+        }
+    }
+
+    fn extractor_for(&self, language: Language) -> Option<&dyn LanguageExtractor> {
+        match language {
+            Language::Rust => Some(&self.rust),
+            Language::Python => Some(&self.python),
+            Language::CSharp => None,
+        }
     }
 }
 
@@ -21,10 +37,9 @@ impl SourceAnalyzer for TreeSitterAnalyzer {
         let source = std::fs::read_to_string(file.path().as_str())
             .map_err(|e| DomainError::IoError(e.to_string()))?;
 
-        match file.language() {
-            Language::Rust => rust::analyze(&source, file.path()),
-            Language::Python => python::analyze(&source, file.path()),
-            Language::CSharp => Ok(AnalysisResult::empty()),
+        match self.extractor_for(file.language()) {
+            Some(extractor) => extractor.analyze(&source, file.path()),
+            None => Ok(AnalysisResult::empty()),
         }
     }
 }