Add to group invite/application system is buggy

We've had a person register for the site (user 2570) but has had real difficulties getting joined to a group.

There seem to be a number of inconsistency bugs here, but I suspect each one can be dealt with fairly easily.

Here's what was done:

Firstly, they created an account in the normal way, which worked fine. However, they found that they couldn't see the private threads of a group (correctly, as they were obviously not a member of the group).

They e-mailed the group. The invite system at /groups/2-camcycle/memberships/new was used. This states "If this matches an existing Cyclescape account they will be added to the group immediately.". They didn't get an e-mail (and confirmed that their mail processing logs shows no bounces), as described in the interface hint in that form. They confirmed that they didn't seem to be able to see the private threads (presumably meaning they are not a member yet).

I then suggested they use the 'Join Group' button at / (i.e. the group's homepage, on their subdomain). The user filled out the form (and said they didn't remember doing this before) - had they done so before I issued the invite I suspect this would have worked straight away.

I have now approved them in the Membership Requests page at /groups/2-camcycle/membership_requests.

However, their status is inconsistent:

• On /groups/2-camcycle/members they are shown as Invite pending. So presumably if there is an approval, all remnants of any invite(s) for a user should be deleted.
• On their profile page, at /users/2570-<moniker>/profile they are shown correctly as a member of the group.
• On /groups/2-camcycle/membership_requests they are correctly shown as Confirmed.

The membership requests page still has a link 'Review' even when a user has been confirmed.

So the bugs here I think are:

1. The invite system doesn't actually seem to be immediately adding a user to the group if the user is already present in Cyclescape.
2. When someone is correctly added to a group (whether by an administrator directly, or by confirming an invite link, or by automatic matching from the potential members system), at that point an e-mail should be sent to them confirming that they have been added, to avoid any ambiguity.
3. Invites pending are still present even after a user is confirmed.
4. Membership requests page still has a link 'Review' even when a user has been confirmed

Start by reproducing the invite, Join Group, approval, members, and membership_requests flows using the routes in the report, including user 2570 and group 2-camcycle. Trace each status transition and notification outcome. Done means existing users are added as promised, receive confirmation email, pending invites disappear after confirmation, and confirmed requests no longer show Review.