feat: add improvements to the http server (#65) * chore(main): Add graceful shutdown to the http service * build(compose): add a health check to the compose file * build(main): rename the temporary path environment variable * build(make): add changes to the makefile * fix(templates): fix zip files preview * fix(docker): add non-root user to the dockerfile * fix(templates): shorten the modal title * build(make): set the build target as prerequisite * feat(main): add api router * refactor(main): refactor the functions and handlers that are responsible to convert input files * docs(README): add documentation on how to use the api