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/domain/src/value_objects/source/module_name.rs

@@ -1,3 +1,6 @@
+use std::collections::HashMap;
+use std::path::Path;
+
 use crate::DomainError;
 
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
@@ -12,6 +15,60 @@ impl ModuleName {
         Ok(Self(trimmed.to_string()))
     }
 
+    pub fn from_path(
+        file_path: &str,
+        root: &Path,
+        module_mappings: &HashMap<String, String>,
+    ) -> Option<Self> {
+        let relative = file_path
+            .strip_prefix(root.to_str().unwrap_or(""))
+            .unwrap_or(file_path)
+            .trim_start_matches('/');
+
+        for (pattern, module_name) in module_mappings {
+            if relative.starts_with(pattern.as_str()) {
+                return Self::new(module_name).ok();
+            }
+        }
+
+        let parts: Vec<&str> = relative.split('/').collect();
+        if parts.len() <= 1 {
+            return None;
+        }
+
+        let module_dir = if (parts[0] == "crates" || parts[0] == "src") && parts.len() > 2 {
+            parts[1]
+        } else if parts[0] != "src" && parts.len() > 1 {
+            parts[0]
+        } else {
+            return None;
+        };
+
+        Self::new(&Self::capitalize(module_dir)).ok()
+    }
+
+    pub fn from_directory_group(member_path: &str) -> Option<Self> {
+        let parts: Vec<&str> = member_path.split('/').collect();
+        if parts.len() < 3 {
+            return None;
+        }
+        let group = parts[parts.len() - 2];
+        Self::new(&Self::capitalize(group)).ok()
+    }
+
+    pub fn capitalize(s: &str) -> String {
+        s.split('-')
+            .map(|seg| {
+                if seg.is_empty() {
+                    String::new()
+                } else {
+                    format!("{}{}", seg[..1].to_uppercase(), &seg[1..])
+                }
+            })
+            .collect::<Vec<_>>()
+            .join("-")
+    }
+
     pub fn as_str(&self) -> &str {
         &self.0
     }