fix(theme): scroll theme list to active theme on open (@abulKhasim) (#7774)

When opening the theme selector, the list always starts at the top 
regardless of the currently active theme. This means users have to 
manually scroll to find their current theme before switching.

This fix scrolls the theme list to the currently active theme when 
the selector is opened, so users immediately see their position in the
list.

Steps to reproduce:
1. Set any theme other than the first one (e.g. blueberry dark)
2. Open the theme selector
3. List starts from the top instead of the active theme

Author: abulKhasim

frontend/src/ts/commandline/commandline.ts

@@ -172,6 +172,7 @@ export function show(
       await showCommands();
       await updateActiveCommand();
       setTimeout(() => {
+        lastActiveIndex = undefined;
         keepActiveCommandInView();
         if (showInputCommand) {
           const escaped =
@@ -488,6 +489,11 @@ async function showCommands(): Promise<void> {
 
   for (const command of list) {
     if (command.found !== true) continue;
+
+    if (command.isActive && firstActive === null && inputValue === "") {
+      firstActive = index;
+    }
+
     let customStyle = "";
     if (command.customStyle !== undefined && command.customStyle !== "") {
       customStyle = command.customStyle;