Recent transactions, Login Codes and Burnout Board improvements

A raft of fixes, tweaks and refinements in this release. 

Improvement 

- Magic login links have been replaced with 6 digit login codes. Codes are just as secure but more reliable than placing links in the body of an email.

- The reports page now has a dropdown for selecting your annual summary reports

Pro 

We've tuned the Burnout Board algorithm to exclude anyone that's currently absent. So someone on long term leave e.g. maternity won't show as a burnout risk. 

Fix 

1) We fixed an issue with recent transactions where some history wouldn't show up for bookings created a long time ago but updated recently. 

2) Any integrations you had set up (Slack, Teams) would switch to "all departments" if you deleted the department they were set up against. Now we'll delete those integrations when the department gets deleted too.

3) We fixed an issue with birthday reminders where they wouldn't go out sometimes.