Fix missing p5. prefix in Simple Melody App tutorial

[aashu2006]

Problem

Line 298 in the Simple Melody App tutorial contains broken code that throws a runtime error:

// Current code (broken)
osc = new Oscillator(myFreq);  // ReferenceError: Oscillator is not defined

Solution

Added the missing p5. prefix:

// Fixed code
osc = new p5.Oscillator(myFreq);  // Works correctly

Why This Fix Is Needed

• Breaks the tutorial for all users at this step
• Inconsistent with other examples in the same tutorial
• Prevents learners from completing the app

Testing

• Tested code with new Oscillator() - confirms error occurs
• Tested code with new p5.Oscillator() - confirms fix works
• Verified consistency with rest of tutorial