feat：记忆&上下文管理

Dockerfile

@@ -9,6 +9,10 @@ ENV UV_PYTHON_DOWNLOADS=never
 COPY pyproject.toml uv.lock ./
 RUN uv sync --locked --no-dev --no-install-project
 
+# 会话历史的预算按 o200k 计数；编码表在构建时下载好，运行时不用再联网
+ENV TIKTOKEN_CACHE_DIR=/app/.tiktoken
+RUN .venv/bin/python -c "import tiktoken; tiktoken.get_encoding('o200k_base')"
+
 FROM python:3.11-slim-bookworm
 
 # PyArrow、DuckDB 的 Linux wheels 需要 C++ 运行库
@@ -19,12 +23,14 @@ RUN apt-get update \
 ENV PYTHONDONTWRITEBYTECODE=1 \
     PYTHONUNBUFFERED=1 \
     PATH="/app/.venv/bin:$PATH" \
+    TIKTOKEN_CACHE_DIR=/app/.tiktoken \
     UVICORN_HOST=0.0.0.0 \
     UVICORN_PORT=8000
 
 WORKDIR /app
 
 COPY --from=builder /app/.venv ./.venv
+COPY --from=builder /app/.tiktoken ./.tiktoken
 COPY app ./app
 COPY mcp_servers ./mcp_servers
 COPY mcp_servers.json ./