Fix progress overlay, play-from-position, layout cutoff, speaker info

- Replace progress bar with task checklist showing pipeline steps
  (load model, transcribe, load diarization, identify speakers, merge)
- Fix WaveformPlayer: track ready state, disable controls until loaded,
  play from current position instead of resetting to start
- Fix workspace height calc to prevent bottom content cutoff
- Show HF_TOKEN setup hint in SpeakerManager when no speakers detected
- Add console logging for progress events to aid debugging

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

python/voice_to_notes/services/pipeline.py

@@ -140,7 +140,7 @@ class PipelineService:
         # Step 3: Merge (or skip if diarization failed)
         if diarization is not None:
             write_message(
-                progress_message(request_id, 90, "pipeline", "Merging transcript with speakers...")
+                progress_message(request_id, 90, "merging", "Merging transcript with speakers...")
             )
             result = self._merge_results(transcription, diarization.speaker_segments)
             result.speakers = diarization.speakers