Fix(spotlight): improve file search query restoration and mode switching (#2887)

* fix(spotlight): fix empty results on restoring last file search query

- When "remember last query" is enabled and the last query is file search, it shows "no results" until the query is manually modified in full launcher mode.

* fix(spotlight): properly restore last selected mode(tab) when enabled in full launcher mode

* fix(spotlight): allow file trigger in plugins mode(tab)

* fix(spotlight): restore previous mode when clearing '/' file search prefix

When the '/' prefix is removed from the query, the controller now correctly reverts to the previous mode instead of remaining stuck in "files" mode.

* fix(spotlight): code review fix

quickshell/Modals/DankLauncherV2/Controller.qml

@@ -449,7 +449,12 @@ Item {
         searchQuery = query;
         requestSearch();
 
-        if (searchMode !== "plugins" && query.startsWith("/")) {
+        if (autoSwitchedToFiles && !query.startsWith("/")) {
+            restorePreviousMode();
+            return;
+        }
+
+        if (query.startsWith("/")) {
             var prefix = Utils.parseFileSearchPrefix(query);
             var explicitType = prefix && prefix.type !== null ? prefix.type : null;
             var targetType = explicitType !== null ? explicitType : (SessionData.launcherLastFileSearchType || "all");