Add an optional expiration date column for urls

[evanugarte]

users should be able to specify an expiration for a url. this expiration would exist as a new column in the sqlite database.

if a url was requested and it had a non-null expiration value, and the url is expired, it is deleted from the database and the api returns a 404.

game plan

• clone cleezy and run it on your computer
• understand how to create a table in sqlite with a simple query
• understand how to add a column to an existing table in sqlite with a query
• change create_url to accept a new parameter expiration_date that is an epoch timestamp (like 1718479172174)
• have create_url store this timestamp in the new column for the url table