chore: add auto pip mirror selection by region

Dockerfile

@@ -5,8 +5,42 @@ WORKDIR /app
 ENV PYTHONDONTWRITEBYTECODE=1 \
     PYTHONUNBUFFERED=1
 
+ARG PIP_INDEX_URL=https://mirrors.cloud.tencent.com/pypi/simple
+ARG PIP_TRUSTED_HOST=mirrors.cloud.tencent.com
+ARG PIP_REGION=auto
+
 COPY requirements.txt /app/requirements.txt
-RUN pip install --no-cache-dir -r /app/requirements.txt
+RUN set -e; \
+    region="${PIP_REGION}"; \
+    if [ "${region}" = "auto" ]; then \
+      region=$(python - <<'PY'
+import urllib.request
+urls = [
+    "https://ipapi.co/country/",
+    "https://ifconfig.co/country-iso",
+]
+for u in urls:
+    try:
+        with urllib.request.urlopen(u, timeout=3) as r:
+            v = r.read().decode("utf-8", errors="ignore").strip().upper()
+            if v:
+                print(v)
+                raise SystemExit(0)
+    except Exception:
+        pass
+print("UNKNOWN")
+PY
+); \
+    fi; \
+    echo "[build] PIP region=${region}"; \
+    if [ "${region}" = "CN" ]; then \
+      pip install --no-cache-dir --retries 5 --timeout 120 \
+        -i "${PIP_INDEX_URL}" --trusted-host "${PIP_TRUSTED_HOST}" \
+        -r /app/requirements.txt \
+      || pip install --no-cache-dir --retries 5 --timeout 120 -r /app/requirements.txt; \
+    else \
+      pip install --no-cache-dir --retries 5 --timeout 120 -r /app/requirements.txt; \
+    fi
 
 COPY app /app/app