search: fix order of result merging

During a search, we get the results from oldest --> newest.
When we hit the more button, we get the results of the second batch
in the same order.
However, logically to the first batch everything is older, so we
need to prepend it to the result array, not
append.

msg  DB  logical ID
A    3     5
B    2     4
C    1     3

D    3     2
E    2     1
F    1     0

client/js/store.ts

@@ -354,7 +354,7 @@ const mutations: Mutations = {
 			return;
 		}
 
-		const results = [...state.messageSearchResults.results, ...value.results];
+		const results = [...value.results, ...state.messageSearchResults.results];
 
 		state.messageSearchResults = {
 			results,