Fix keyboard shortcut support and address code review feedback

- Add editBranchPrefixCommand in note_tree.ts to support F2 keyboard shortcut with multi-selection
- Extract CSS to separate branch_prefix.css file
- Remove hard-coded color, use CSS class instead
- Fix translation key usage to keep t() calls visible in IDE
- Remove all inline styles

Co-authored-by: eliandoran <21236836+eliandoran@users.noreply.github.com>

apps/client/src/widgets/note_tree.ts

@@ -1591,6 +1591,20 @@ export default class NoteTreeWidget extends NoteContextAwareWidget {
         this.clearSelectedNodes();
     }
 
+    async editBranchPrefixCommand({ node }: CommandListenerData<"editBranchPrefix">) {
+        const branchIds = this.getSelectedOrActiveBranchIds(node).filter((branchId) => !branchId.startsWith("virt-"));
+
+        if (!branchIds.length) {
+            return;
+        }
+
+        // Trigger the event with the selected branch IDs
+        appContext.triggerEvent("editBranchPrefix", {
+            selectedOrActiveBranchIds: branchIds,
+            node: node
+        });
+    }
+
     canBeMovedUpOrDown(node: Fancytree.FancytreeNode) {
         if (node.data.noteId === "root") {
             return false;