feat: allow sign in with email

[stonith404]

This feature resolves #18 which suggest that users should be able to sign in with an link sent to their email. This function is only recommended for environment where security isn't a big concern like hosting it in the local network.

The feature has to be enabled in the settings:

[samiralam]

Seems to work as advertised!

Some feedback:

• Suggest changing the link text from "You don't have access to your passkey?" to "Don't have access to your passkey?" as a more natural English phrase
• Recommend adding the ability to enable email logins separately from email notifications; currently there's no way to enable the first while disabling the second. While "new device" email notifications are a good idea, currently it sends an email every time I login, even from the same device, which gets a bit spammy.

[stonith404]

@samiralam Thanks for your feedback. These two changes are now implemented in the latest stonith404/pocket-id:dev-email-login image.

[samiralam]

Pulled the new image and retested:

• Updated link text
• Email login link redirects to client after logging in
• Email notifications can be enabled separately from email logins

Looks great!