fix: always use detect_language for Deepgram file transcription

Deepgram's `language` parameter enforces a specific language and returns
empty results when the audio doesn't match. Removed the language pass-through
so detect_language=true is always used, preventing empty transcriptions.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: XimilalaXiang

frontend/src/hooks/useFileTranscription.ts

@@ -711,13 +711,11 @@ async function executeDeepgram(
   updateJob(jobId, { status: 'uploading', progress: 20 })
 
   updateJob(jobId, { status: 'transcribing', progress: 40 })
-  const singleLang = config.languageHints?.length === 1 ? config.languageHints[0] : undefined
   const response = await deepgramTranscribeFile(
     apiKey,
     file,
     {
       model: config.model || 'nova-3',
-      language: singleLang,
       diarize: config.enableSpeakerDiarization,
       punctuate: true,
       utterances: true,