Rollback web speaker diarization; HF token helper for whisper_stt

- Remove app/diarize.py and pyannote from requirements.txt; web uses faster-whisper only
- Revert main.py job/transcribe flow and index.html meta/hints
- Add app/pyannote_auth.py for Pipeline.from_pretrained(..., token=...) used by whisper_stt
- Expand whisper_stt / README / requirements-whisper-stt for gated repos (community-1, 403)

Made-with: Cursor

app/pyannote_auth.py

@@ -0,0 +1,26 @@
+"""pyannote 파이프라인은 config가 허브의 gated 하위 모델(segmentation·embedding 등)을 가리킬 수 있어 토큰이 필요하다."""
+from __future__ import annotations
+
+import os
+from pathlib import Path
+from typing import Any
+
+
+def hf_token_for_pyannote() -> str | bool:
+    """명시 토큰 또는 True(= huggingface-cli 로그인 캐시)."""
+    for key in ("HF_TOKEN", "HUGGING_FACE_HUB_TOKEN", "PYANNOTE_AUTH_TOKEN"):
+        v = os.environ.get(key, "").strip()
+        if v:
+            return v
+    return True
+
+
+def load_pyannote_pipeline(model_dir: str | Path) -> Any:
+    from pyannote.audio import Pipeline
+
+    auth = hf_token_for_pyannote()
+    path = str(model_dir)
+    try:
+        return Pipeline.from_pretrained(path, token=auth)
+    except TypeError:
+        return Pipeline.from_pretrained(path, use_auth_token=auth)