feat(tasks): finished work can be looked at, and is out of the way by default

A task list is what is left to do, so closing something has to take it off the
plan. But "what did I get done" is a real question and the answer was nowhere:
once a task was closed it left the interface entirely.

They come back in one list at the bottom rather than back among the open ones in
their sections. A closed task has stopped being work and started being a record,
and putting the record in the middle of the plan makes the plan longer without
making it say more.

Off by default, and deliberately: a list that opens full of things already done is
a list you have to read past before you can use it.

In localStorage rather than on the account, like the sidebar's width and unlike a
folded group. It is a way of *looking*, not a statement about the work — somebody
reviewing their week wants it on for ten minutes, and a setting that followed them
to every device is one they would have to turn off twice.

`loadTasks` asks for closed tasks when the setting is on, rather than each caller
deciding. A view added later cannot then forget and quietly ignore it.

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

web/src/lib/locales/da.js

@@ -583,5 +583,9 @@ export const da = {
 	'push.deniedByBrowser':
 		'Browseren har blokeret notifikationer for dette site. Det skal slås til i browserens indstillinger.',
 	'push.notEnabled': 'Notifikationer blev ikke slået til.',
-	'push.noVapidKey': 'Serveren har ingen VAPID-nøgle.'
+	'push.noVapidKey': 'Serveren har ingen VAPID-nøgle.',
+
+	'view.done': 'Færdige',
+	'view.showDone': 'Vis færdige',
+	'view.hideDone': 'Skjul færdige'
 };