Challenge: Phonebook Application

Create a simple phonebook application using a dictionary to manage contacts. Implement three functions: one to add contacts, one to search for a contact by name, and one to delete a contact by name.

• Add a contact by setting the provided name as the key and the number as the value in the dictionary.
• Search for a contact by name and return the associated number if found, or the string "Contact not found" if the name does not exist in the dictionary.
• Delete a contact by name and return true if the contact was deleted, or false if the name was not found in the dictionary.