feat(stt-log): log the WHOLE turn pipeline to the transcript channel

The transcript channel only showed successful transcripts, so dropped utterances
(the 47/50 misses) were invisible. Now every captured utterance is mirrored with
its outcome and per-stage timing:
- too-short blip (<300ms), VAD "음성 아님(VAD 차단)", "인식 실패", "답변 없음", or "ok"
- transcript + reply (or "(무응답)")
- ⏱️ stt/llm seconds

The bridge meta now carries note + stt_sec + think_sec; voice.ts fires onTurn for
every turn (not only non-empty transcripts) and for the too-short drop; userbot
formats the diagnostic line.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

bridge/server.py

@@ -211,7 +211,7 @@ def transcribe(wav_bytes: bytes) -> dict:
         log=lambda m: print(f"[bridge] {m}", flush=True),
     ):
         print("[bridge] no speech detected (VAD) — skipping STT", flush=True)
-        return {"text": "", "language": None}
+        return {"text": "", "language": None, "note": "음성 아님(VAD 차단)"}
 
     segments, info = _whisper.transcribe(audio, beam_size=1, language=STT_LANGUAGE)
     # Second line of defence: drop non-speech / hallucinated segments by
@@ -231,7 +231,8 @@ def transcribe(wav_bytes: bytes) -> dict:
         log=lambda m: print(f"[bridge] {m}", flush=True),
     )
     text = "".join(seg.text for seg in kept).strip()
-    return {"text": text, "language": getattr(info, "language", None)}
+    note = "ok" if text else "인식 실패(빈 결과/필터)"
+    return {"text": text, "language": getattr(info, "language", None), "note": note}
 
 
 def think(text: str, language: Optional[str] = None, broadcasting: Optional[bool] = None) -> dict:
@@ -458,7 +459,9 @@ def http_converse_stream():
         transcript = stt.get("text", "")
         if not transcript:
             yield json.dumps({"type": "meta", "transcript": "", "language": stt.get("language"),
-                              "reply": "", "error": stt.get("error"), "broadcast_action": None}) + "\n"
+                              "reply": "", "error": stt.get("error"),
+                              "note": stt.get("note", "빈 결과"),
+                              "stt_sec": round(t_stt - t0, 1), "broadcast_action": None}) + "\n"
             yield json.dumps({"type": "end"}) + "\n"
             return
         result = think(transcript, stt.get("language"), broadcasting)
@@ -470,6 +473,9 @@ def http_converse_stream():
             "language": stt.get("language"),
             "reply": reply,
             "error": result.get("error"),
+            "note": "ok" if reply.strip() else "답변 없음",
+            "stt_sec": round(t_stt - t0, 1),
+            "think_sec": round(t_think - t_stt, 1),
             "broadcast_action": result.get("broadcast_action"),
         }) + "\n"
         tts_total = 0.0