fix: remove negative number literal parsing in lexer and update tests for unary minus precedence

The lexer previously treated a leading minus sign followed by a digit as a single negative number token, which caused incorrect parsing of expressions like `1-1` and broke method calls on negative numbers. This change removes that special case, making the minus sign always a separate token, and updates all test expectations to use explicit parentheses for negative number method calls.

src/wren_compiler.c

@@ -752,14 +752,7 @@ static void nextToken(Parser* parser)
         return;
 
       case '-':
-        if (isDigit(peekChar(parser)))
-        {
-          readNumber(parser);
-        }
-        else
-        {
-          makeToken(parser, TOKEN_MINUS);
-        }
+        makeToken(parser, TOKEN_MINUS);
         return;
 
       case '|':