Add Merge UI to V2 (#4235)

# Description of Changes
Add UI for Merge into V2.

frontend/src/components/tools/shared/FileStatusIndicator.tsx

@@ -10,11 +10,12 @@ import { StirlingFile } from "../../../types/fileContext";
 
 export interface FileStatusIndicatorProps {
   selectedFiles?: StirlingFile[];
-  placeholder?: string;
+  minFiles?: number;
 }
 
 const FileStatusIndicator = ({
   selectedFiles = [],
+  minFiles = 1,
 }: FileStatusIndicatorProps) => {
   const { t } = useTranslation();
   const { openFilesModal, onFilesSelect } = useFilesModalContext();
@@ -55,6 +56,14 @@ const FileStatusIndicator = ({
     return null;
   }
 
+  const getPlaceholder = () => {
+    if (minFiles === undefined || minFiles === 1) {
+      return t("files.selectFromWorkbench", "Select files from the workbench or ");
+    } else {
+      return t("files.selectMultipleFromWorkbench", "Select at least {{count}} files from the workbench or ", { count: minFiles });
+    }
+  };
+
   // Check if there are no files in the workbench
   if (stirlingFileStubs.length === 0) {
     // If no recent files, show upload button
@@ -89,12 +98,12 @@ const FileStatusIndicator = ({
   }
 
   // Show selection status when there are files in workbench
-  if (selectedFiles.length === 0) {
+  if (selectedFiles.length < minFiles) {
     // If no recent files, show upload option
     if (!hasRecentFiles) {
       return (
         <Text size="sm" c="dimmed">
-          {t("files.selectFromWorkbench", "Select files from the workbench or ") + " "}
+          {getPlaceholder() + " "}
           <Anchor
             size="sm"
             onClick={handleNativeUpload}
@@ -109,7 +118,7 @@ const FileStatusIndicator = ({
       // If there are recent files, show add files option
       return (
         <Text size="sm" c="dimmed">
-          {t("files.selectFromWorkbench", "Select files from the workbench or ") + " "}
+          {getPlaceholder() + " "}
           <Anchor
             size="sm"
             onClick={() => openFilesModal()}
@@ -125,7 +134,7 @@ const FileStatusIndicator = ({
 
   return (
    <Text size="sm" c="dimmed" style={{ wordBreak: 'break-word', whiteSpace: 'normal' }}>
-        ✓ {selectedFiles.length === 1 ? t("fileSelected", "Selected: {{filename}}", { filename: selectedFiles[0]?.name }) : t("filesSelected", "{{count}} files selected", { count: selectedFiles.length })}
+      ✓ {selectedFiles.length === 1 ? t("fileSelected", "Selected: {{filename}}", { filename: selectedFiles[0]?.name }) : t("filesSelected", "{{count}} files selected", { count: selectedFiles.length })}
     </Text>
   );
 };