Let a PC be assigned a business unit, and a retired asset be found

The last two items from the run.

The PC detail page has always rendered a Business Unit row, and the API has
always accepted the field. Only the form had no control, so it could be read and
never set from the UI - a value that appeared the moment somebody set it through
the API and could not be reached otherwise. The form has the picker now, loaded
with listAll() rather than a capped page.

Global search excluded inactive assets, so a retired record existed, was
reachable by URL, and could not be found by anybody who did not already know
where it was - including whoever wanted to restore it, which the retire dialog
promises they can. Retired assets are searchable now.

That is only safe with the ordering, so it is part of the change rather than a
follow-up: somebody searching a machine number almost always wants the machine
still on the floor, so a retired match drops 60 points of relevance, sorts below
every live one, and carries a 'retired' flag the results page renders as a
badge. Indistinguishable retired results would be worse than none.

Four tests, verified by planting the isactive filter back: three fail.

Scope: product

frontend/src/views/SearchResults.vue

@@ -83,6 +83,12 @@
                 <span v-if="result.location" class="result-location">{{ result.location }}</span>
                 <span v-if="result.ticketnumber" class="result-ticket">{{ result.ticketnumber }}</span>
                 <span v-if="result.iscurrent" class="badge badge-success">Active</span>
+                <!-- Retired assets are searchable on purpose (the retire
+                     dialog promises they can be restored, and the search box
+                     is where somebody looks for one). They rank below live
+                     assets and say so, or a retired record looks like a
+                     current one. -->
+                <span v-if="result.retired" class="badge badge-secondary">retired</span>
               </div>
             </div>
             <button