feat: consumption log top1 + elapsed since recording; RTSP play once

- Add top1_name/top1_conf to TSV and show top1–3 in pending markdown
- Add 相对开录 column and pass since_recording_start from surgery start
- Track surgery_started_wall and format_elapsed_mmss_since in session registry
- Remove ffmpeg stream_loop from synthetic/demo fake RTSP (play once)
- Fix fake_rtsp_from_file poll loop indentation; update README
- Extend consumption TSV tests; add face test PNGs under tests/faces

Made-with: Cursor

app/services/video/session_registry.py

@@ -29,6 +29,16 @@ from app.services.voice_confirm import build_prompt_text
 from app.surgery_errors import SurgeryPipelineError
 
 
+def format_elapsed_mmss_since(surgery_started_wall: float | None, *, at_epoch: float) -> str:
+    """从 ``start_surgery`` 记录的开录时刻到 ``at_epoch`` 的流逝时间（分+秒），供终端 loguru 使用。"""
+    if surgery_started_wall is None:
+        return "—"
+    sec = max(0.0, at_epoch - surgery_started_wall)
+    total = int(sec)
+    m, s = divmod(total, 60)
+    return f"{m}分{s:02d}秒"
+
+
 @dataclass
 class PendingConsumableConfirmation:
     """待客户端确认的一条低置信度识别（不阻塞后续帧推理）。"""
@@ -73,6 +83,8 @@ class SurgerySessionState:
     last_asr_text: str | None = None
     #: 最近一次语音确认错误说明（ASR/解析失败等）。
     last_voice_error: str | None = None
+    #: ``start_surgery`` 创建会话时的 ``time.time()``，用于日志中「相对开录的流逝时间」。
+    surgery_started_wall: float | None = None
 
 
 @dataclass