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/syntax/lexer.rs

@@ -31,6 +31,14 @@ pub enum Token {
     Species,
     #[token("enum")]
     Enum,
+    #[token("concept")]
+    Concept,
+    #[token("sub_concept")]
+    SubConcept,
+    #[token("concept_comparison")]
+    ConceptComparison,
+    #[token("any")]
+    Any,
     #[token("state")]
     State,
     #[token("on")]
@@ -509,4 +517,21 @@ Second prose block content.
             vec![Token::IntLit(20), Token::DotDot, Token::IntLit(40),]
         );
     }
+
+    #[test]
+    fn test_type_system_keywords() {
+        let input = "concept sub_concept concept_comparison any";
+        let lexer = Lexer::new(input);
+        let tokens: Vec<Token> = lexer.map(|(_, tok, _)| tok).collect();
+
+        assert_eq!(
+            tokens,
+            vec![
+                Token::Concept,
+                Token::SubConcept,
+                Token::ConceptComparison,
+                Token::Any,
+            ]
+        );
+    }
 }