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.

tests/validate_examples.rs

@@ -24,7 +24,7 @@ fn load_example(name: &str) -> Project {
 
     assert!(path.exists(), "Example '{}' not found at {:?}", name, path);
 
-    Project::load(&path).expect(&format!("Failed to load example '{}'", name))
+    Project::load(&path).unwrap_or_else(|_| panic!("Failed to load example '{}'", name))
 }
 
 // ============================================================================