chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/anthropic/_constants.py

@@ -0,0 +1,29 @@
+# File generated from our OpenAPI spec by Stainless. See CONTRIBUTING.md for details.
+
+import httpx
+
+RAW_RESPONSE_HEADER = "X-Stainless-Raw-Response"
+OVERRIDE_CAST_TO_HEADER = "____stainless_override_cast_to"
+
+# default timeout is 10 minutes
+DEFAULT_TIMEOUT = httpx.Timeout(timeout=10 * 60, connect=5.0)
+DEFAULT_MAX_RETRIES = 2
+DEFAULT_CONNECTION_LIMITS = httpx.Limits(max_connections=1000, max_keepalive_connections=100)
+
+INITIAL_RETRY_DELAY = 0.5
+MAX_RETRY_DELAY = 8.0
+
+HUMAN_PROMPT = "\n\nHuman:"
+
+AI_PROMPT = "\n\nAssistant:"
+
+MODEL_NONSTREAMING_TOKENS = {
+    "claude-opus-4-20250514": 8_192,
+    "claude-opus-4-0": 8_192,
+    "claude-4-opus-20250514": 8_192,
+    "anthropic.claude-opus-4-20250514-v1:0": 8_192,
+    "claude-opus-4@20250514": 8_192,
+    "claude-opus-4-1-20250805": 8192,
+    "anthropic.claude-opus-4-1-20250805-v1:0": 8192,
+    "claude-opus-4-1@20250805": 8192,
+}