feat(worker): 接口1 四庭七眼测量真实实现（替换 Mock）

worker 侧从 Mock 替换为真实算法：
- face_analysis 包：detector(MediaPipe 478点) / pose(solvePnP 姿态) /
  calibration(虹膜直径法) / hair_segmenter+bisenet_model(方案B 头发分割) /
  measure(方案A兜底+B/A决策+七眼+换算) / annotation(numpy渐变线+中文标注)
- app.py：/api/v1/face/measure 接真实实现，返回 annotated_image_base64
  （不落盘不拼URL，落盘由网关做）；加 X-Internal-Token 鉴权、/health 就绪态、
  可配置分辨率门槛、异常兜底
- 部署：start.sh/run_worker.sh/hair-worker.service 监听 8187；worker_config 示例
- 测试 tests/：Tier1合成真值<1e-6 + Tier2缩放不变 + Tier3叠加 + 错误码集成 +
  数值回归，pytest 24 项全绿
- 文档补实测基线表 + RTX5090/torch 说明

注：worker 为 RTX 5090(sm_120)，pinned torch 2.2.2(cu121) 只到 sm_90，
BiSeNet 已自动回退 CPU（方案B 正常）；要用 GPU 需换 torch cu128(≥2.7)。

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

scripts/download_weights.sh

@@ -0,0 +1,39 @@
+#!/usr/bin/env bash
+# 下载接口1（四庭七眼测量）所需的模型权重与中文字体。
+# 内网/离线环境无需执行：文件已随仓库带入（见 OFFLINE_ASSETS.md）。
+# 仅供联网环境（生产机重建）使用。
+set -euo pipefail
+
+ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+WEIGHTS="$ROOT/face_analysis/weights"
+FONTS="$ROOT/face_analysis/fonts"
+mkdir -p "$WEIGHTS" "$FONTS"
+
+# BiSeNet 主权重（~53MB）
+if [ ! -f "$WEIGHTS/79999_iter.pth" ]; then
+  echo ">> 下载 BiSeNet 主权重 79999_iter.pth"
+  curl -L -o "$WEIGHTS/79999_iter.pth" \
+    "https://huggingface.co/ManyOtherFunctions/face-parse-bisent/resolve/main/79999_iter.pth"
+fi
+
+# BiSeNet 骨干 resnet18（~45MB）
+if [ ! -f "$WEIGHTS/resnet18-5c106cde.pth" ]; then
+  echo ">> 下载 resnet18 骨干 resnet18-5c106cde.pth"
+  curl -L -o "$WEIGHTS/resnet18-5c106cde.pth" \
+    "https://download.pytorch.org/models/resnet18-5c106cde.pth"
+fi
+
+# 中文字体（思源黑体，~16MB）
+if [ ! -f "$FONTS/NotoSansCJKsc-Regular.otf" ]; then
+  echo ">> 下载中文字体 NotoSansCJKsc-Regular.otf"
+  curl -L -o "$FONTS/NotoSansCJKsc-Regular.otf" \
+    "https://github.com/notofonts/noto-cjk/raw/main/Sans/OTF/SimplifiedChinese/NotoSansCJKsc-Regular.otf"
+fi
+
+# resnet18 骨干放进 torch 缓存，避免 BiSeNet 初始化联网下载
+CACHE="$HOME/.cache/torch/hub/checkpoints"
+mkdir -p "$CACHE"
+cp -n "$WEIGHTS/resnet18-5c106cde.pth" "$CACHE/" || true
+
+echo ">> 完成。校验 sha256（见 OFFLINE_ASSETS.md）："
+sha256sum "$WEIGHTS/79999_iter.pth" "$WEIGHTS/resnet18-5c106cde.pth" "$FONTS/NotoSansCJKsc-Regular.otf"