password strength

We use zxcvbn to help our users secure their Coil accounts by giving them tips, and warnings about their passwords.

A few examples of some tips are warnings:
"This is a top-100 common password"
"Predictable subsctitutions like '@' instead of 'a' don't help very much"
"Repeats like "abcabcabc" are only slightly harder to guess than "abc"

We hope this helps people create more secure passwords if they are not already using a password manager.