Add .gitignore and clean up repository for Course Management System

[Copilot]

This PR adds proper version control hygiene to the Course Management System repository by implementing a comprehensive .gitignore file and removing compiled artifacts from tracking.

Changes Made

Added .gitignore File

Created a comprehensive .gitignore file to exclude:

• Compiled Java class files (*.class)
• Package files (*.jar, *.war, *.ear)
• IDE-specific files (.idea/, .vscode/, etc.)
• OS-specific files (.DS_Store, Thumbs.db)

Repository Cleanup

• Removed all compiled .class files from version control
• These files were previously tracked but should be generated during build time
• The .gitignore ensures they won't be accidentally committed in the future

Verification

The Course Management System continues to work perfectly after these changes:

javac *.java
java Main

Output:

=== Course Management System ===
Module: Computer Science Course
  Module: Programming Fundamentals
  Lesson: Java Basics | Duration: 2 hours | Instructor: Prof. Smith
  Lesson: OOP Concepts | Duration: 3 hours | Instructor: Prof. Johnson
  Lesson: Data Structures | Duration: 4 hours | Instructor: Prof. Brown

Why This Matters

• Clean Repository: Only source code and documentation are now tracked
• Build Reproducibility: Compiled artifacts are generated fresh each time
• Cross-Platform Compatibility: Avoids issues with class files compiled on different Java versions
• Best Practices: Follows standard Java project conventions for version control

The core implementation of the Composite Design Pattern remains unchanged and fully functional.

Created from VS Code via the GitHub Pull Request extension.

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