#6 - handle registration form

[jsawo]

Adds registration form handling.
We're using Symfony/Mailer to send emails with a SMTP server provided with .env.
As a consequence, this now depends on PHP.

• form input is validated
• validation errors are reported to the user
• valid form submission results in 2 emails being sent:
  • one email with confirmation to the user that filled the form
  • another - registration notice - to an email configurable in .env

also note:

• form handling on the frontend is done with some HTMX magic
• confirmation email template is based on https://github.com/leemunroe/responsive-html-email-template, simplified a little but should be safe to use
• we don't have the complete email template content yet so that's TBD

further steps that we might consider:

• implement CSRF
• implement confirmation link sent to users

closes #6

[mtracz]

@krzysztofrewak @jsawo
Why we didn't use framework for this stuff and the whole project? As we can see right now, static site is not 100% static site.

Sending 2 emails in sync mode might take some time. Also receiving registration confirmations on email and manage that wont be easy. For this case I would like to use simple CRUD on the backend.
Using framework will give us more powerful and useful tools, like sends reminders to the registered users, confirm email first to prevent spam from 10 minute mail. Use queue to send emails, and so on.

further steps that we might consider:

implement CSRF
implement confirmation link sent to users

Are we going to reinvent "the wheel" again?