feat(lexer): add type system keywords

Added four keywords for new type system:
- concept: Base type definition
- sub_concept: Enum/record sub-type definition
- concept_comparison: Compile-time enum mapping
- any: Universal type for dynamic contexts

Also added:
- CLAUDE.md with project instructions and commit guidelines
- Test coverage for new keywords
- Crate-level deny directives for unused variables and dead code

Fixed pre-existing clippy issues to pass pre-commit hooks.

src/lsp/tests.rs

@@ -481,14 +481,14 @@ mod definition_tests {
         };
 
         let uri = Url::parse("file:///test.sb").unwrap();
-        let result = definition::get_definition(&mut doc, &params, &uri);
+        let result = definition::get_definition(&doc, &params, &uri);
 
         assert!(result.is_some());
     }
 
     #[test]
     fn test_goto_definition_not_found() {
-        let mut doc = Document::new("character Alice {}".to_string());
+        let doc = Document::new("character Alice {}".to_string());
 
         let params = GotoDefinitionParams {
             text_document_position_params: TextDocumentPositionParams {
@@ -505,7 +505,7 @@ mod definition_tests {
         };
 
         let uri = Url::parse("file:///test.sb").unwrap();
-        let result = definition::get_definition(&mut doc, &params, &uri);
+        let result = definition::get_definition(&doc, &params, &uri);
 
         assert!(result.is_none());
     }
@@ -542,7 +542,7 @@ mod references_tests {
         };
 
         let uri = Url::parse("file:///test.sb").unwrap();
-        let result = references::find_references(&mut doc, &params, &uri);
+        let result = references::find_references(&doc, &params, &uri);
 
         assert!(result.is_some());
         let locations = result.unwrap();
@@ -576,7 +576,7 @@ mod references_tests {
         };
 
         let uri = Url::parse("file:///test.sb").unwrap();
-        let result = references::find_references(&mut doc, &params, &uri);
+        let result = references::find_references(&doc, &params, &uri);
 
         let locations = result.unwrap();
         // Should only find "Alice", not "Alicia"