fix(agent): add libpq5 system dep for psycopg v3 (langgraph checkpoint)

docker/Dockerfile.agent

@@ -16,9 +16,9 @@ FROM python:3.11-slim
 
 WORKDIR /app
 
-# Install system deps for pdfplumber
+# Install system deps for pdfplumber + psycopg (v3 needs libpq)
 RUN apt-get update && apt-get install -y --no-install-recommends \
-    libgl1 libglib2.0-0 && rm -rf /var/lib/apt/lists/*
+    libgl1 libglib2.0-0 libpq5 && rm -rf /var/lib/apt/lists/*
 
 # Python dependencies — agent runtime (gradio, langgraph, httpx, pdfplumber, ...)
 # Без sentence-transformers — embedding router безопасно отключается при ImportError.