i18n(transcription): add reader read-label and panel title strings (#697)

transcription_read_label ("Transkription lesen") for the read-only entry
control and transcription_panel_title ("Transkription") for the plain
header readers see instead of the Lesen/Bearbeiten toggle.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/src/lib/document/DocumentTopBar.svelte

@@ -28,6 +28,7 @@ type Doc = {
 	location?: string | null;
 	status?: string | null;
 	tags?: Tag[] | null;
+	hasTranscription?: boolean;
 };
 
 type GeschichteSummary = {
@@ -132,6 +133,7 @@ const overflowPersons = $derived(receivers.slice(2));
 				documentId={doc.id}
 				canWrite={canWrite}
 				isPdf={!!isPdf}
+				hasTranscription={!!doc.hasTranscription}
 				bind:transcribeMode={transcribeMode}
 				filePath={doc.filePath}
 				originalFilename={doc.originalFilename}
@@ -143,6 +145,7 @@ const overflowPersons = $derived(receivers.slice(2));
 					<DocumentMobileMenu
 						canWrite={canWrite}
 						isPdf={!!isPdf}
+						hasTranscription={!!doc.hasTranscription}
 						bind:transcribeMode={transcribeMode}
 						filePath={doc.filePath}
 						originalFilename={doc.originalFilename}