feat(views): "Venter på andre", and a project you share stays yours

`assignee_id` has been on tasks since sharing was built and delegating has
been possible from the drawer since yesterday. What was missing was
anywhere to see it: work handed to somebody else left your lists and
appeared in nothing.

GET /delegated returns everything assigned to somebody who is not you, in
the projects you can see, grouped by the person. Grouped on the server
rather than flat, because the question is about people — "what is Anders
sitting on" — and a client cannot group it itself: it would need the name
behind an assignee id from a project it does not happen to have open, and
there is no way to ask for that. The names come back with the tasks, so
one request is one screen.

The filter is a field of its own rather than a sentinel in AssigneeID.
"What is on my plate" and "what have I handed over" are different
questions, and one string that means an id most of the time and a magic
word the rest is a field somebody eventually passes a real id to.

An assignee whose account is gone is named "Ukendt" rather than dropped.
Losing the row would make work disappear from the one view that exists to
stop work disappearing.

The sidebar entry only appears where delegating is possible at all. On an
instance with one person it could never have anything in it, and a
permanent empty entry is a question the sidebar keeps asking and answering
"no".

Building it turned up a bug in the split above it. "Projekter" and "Delt
med mig" were divided on `shared`, which only means the project has more
than one member — so inviting somebody to a project of your own moved it
under "Delt med mig", where it lost its place in the order, stopped being
draggable, and could not be filed under a group. It is divided on
ownership now, which is what the two headings have always said. Sharing
your own project is not the same event as somebody sharing theirs with
you.

The smoke test now follows the whole loop in one go: invite, accept in a
second browser, assign a task to the person who just joined, and find it
under their name — with the shared project still under "Projekter" on the
way past.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

README.md

@@ -62,6 +62,7 @@ Apple Reminders, forward mail into it, and add it to Claude as a connector.
 | Project roles and permission checks | Done, tested |
 | REST API: projects, sections, tasks, sub-tasks, ordering | Done, tested |
 | Today, Upcoming, search, activity log | Done, tested |
+| Waiting on others: what you have delegated, by person | Done, tested |
 | Sharing: invites, roles, members | Done, tested |
 | Live sync over WebSocket | Done |
 | Web interface: sign-in, views, quick add, ⌘K, shortcuts | Done |