fix: log underlying network error cause for failed transcription requests

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

server/config/transcription.js

@@ -62,7 +62,10 @@ export async function requestTranscription({ meetingId, recordingId, prompt }) {
     log.server.info(`Transcription requested for recording ${recordingId} (meeting: ${meetingId})`);
     return true;
   } catch (err) {
-    log.server.error(`Transcription request error: ${err.message}`);
+    // undici wraps the real network error (ECONNREFUSED, ENOTFOUND, timeout, …)
+    // in err.cause — surface it, "fetch failed" alone is undiagnosable.
+    const cause = err.cause ? ` (${err.cause.code || ''} ${err.cause.message || ''})`.trimEnd() : '';
+    log.server.error(`Transcription request to ${url} failed: ${err.message}${cause}`);
     return false;
   }
 }