FX.128 Team member pictures: built-in defaults, upload, change

SuperCad Teams member page showed only a letter in a circle. A person now has a picture: the default is their initials on a colour, or one of 12 built-in pictures in 8 colours, or an uploaded image (cut to a 128 px square in the page, kept under 24 KB). Change it under Details > Edit. Stored on the person row (people.avatar, account DB schema 4), synced like title and company; the server and the plug-in both refuse anything that is not a built-in or a small png/jpeg/webp. Tests added (teams 310, user-teams 116). Not done: the account's own profile picture is not used as the default; no website member page picture; other-language strings still English; never opened in a real browser window.