fix(parser): Phase 33-10 - Fix NyashTokenizer import in assignment_expr_parser tests

- Fixed incorrect import: crate::tokenizer::Tokenizer → crate::tokenizer::NyashTokenizer
- Updated test code to use NyashTokenizer API (new + tokenize()) instead of static method
- Fixes compilation error preventing cargo build and tests

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

src/parser/stage3/assignment_expr_parser.rs

@@ -107,14 +107,15 @@ impl NyashParser {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use crate::tokenizer::Tokenizer;
+    use crate::tokenizer::NyashTokenizer;
 
     #[test]
     fn test_grouped_assignment_simple() {
         std::env::set_var("NYASH_FEATURES", "stage3");
 
         let input = "local y = (x = 42)";
-        let tokens = Tokenizer::tokenize(input).unwrap();
+        let mut tokenizer = NyashTokenizer::new(input);
+        let tokens = tokenizer.tokenize().unwrap();
         let mut parser = NyashParser::new(tokens);
 
         // Skip 'local' and 'y' and '='