Only record query breadcrumbs when the search is submitted

Queries were previously stored whenever a result was selected, which
meant half-typed queries ended up in the history. Now a query is only
recorded when the user submits the search field, while selecting a
result only records the room.

UnitTests/Sources/SearchScreenViewModelTests.swift

@@ -127,16 +127,26 @@ struct SearchScreenViewModelTests {
     
     @Test
     func selectionRecordsBreadcrumbs() {
+        // Typing alone doesn't record the query, only submitting it does.
         context.searchQuery = "Second"
         context.send(viewAction: .selectRoom(roomID: "2"))
         
-        #expect(userSettings.searchBreadcrumbs == [.room(roomID: "2"), .query("Second")])
+        #expect(userSettings.searchBreadcrumbs == [.room(roomID: "2")])
+        
+        context.send(viewAction: .submitQuery)
+        
+        #expect(userSettings.searchBreadcrumbs == [.query("Second"), .room(roomID: "2")])
         
         // Selecting the same room again from the empty state only bumps it back to the top.
         context.searchQuery = ""
         context.send(viewAction: .selectRoom(roomID: "2"))
         
         #expect(userSettings.searchBreadcrumbs == [.room(roomID: "2"), .query("Second")])
+        
+        // Submitting an empty query records nothing.
+        context.send(viewAction: .submitQuery)
+        
+        #expect(userSettings.searchBreadcrumbs == [.room(roomID: "2"), .query("Second")])
     }
     
     @Test