Fix missing i18n placeholders in OpenInFlexModal (#2269)

Author: myieye

frontend/src/routes/(authenticated)/project/[project_code]/+page.svelte

@@ -361,7 +361,7 @@
         </Button>
       {:else if canSyncProject}
         {#if project && project.type === ProjectType.FlEx && !isEmpty}
-          <OpenInFlexModal bind:this={openInFlexModal} {project}/>
+          <OpenInFlexModal bind:this={openInFlexModal} {project} login={user.emailOrUsername}/>
           <OpenInFlexButton projectId={project.id} onclick={openInFlexModal?.open}/>
         {:else}
           <Dropdown>

frontend/src/routes/(authenticated)/project/[project_code]/OpenInFlexModal.svelte

@@ -9,9 +9,10 @@
 
   interface Props {
     project: Project;
+    login: string;
   }
 
-  const { project }: Props = $props();
+  const { project, login }: Props = $props();
   let modal: Modal | undefined = $state();
 
   export async function open(): Promise<void> {
@@ -35,11 +36,11 @@
     <div class="collapse collapse-arrow">
       <input type="checkbox" />
       <h3 class="collapse-title my-0 px-0 pb-0">
-        {$t('project_page.get_project.instructions_header', { type: project.type, mode: 'manual' })}...
+        {$t('project_page.get_project.instructions_header', { type: project.type, mode: 'manual', isEmpty: 'false' })}...
       </h3>
       <div class="collapse-content p-0">
         <div class="divider mt-0"></div>
-        <Markdown md={$t('project_page.get_project.instructions_flex', { code: project.code, name: project.name })} />
+        <Markdown md={$t('project_page.get_project.instructions_flex', { code: project.code, login, name: project.name })} />
         <SendReceiveUrlField projectCode={project.code} />
       </div>
     </div>