chore: add Python and LangGraph stuff

backend/.python-version

@@ -0,0 +1 @@
+3.12

backend/Makefile

@@ -0,0 +1,5 @@
+install:
+	uv sync
+
+dev:
+	uvx --refresh --from "langgraph-cli[inmem]" --with-editable . --python 3.12 langgraph dev --no-browser --allow-blocking

backend/langgraph.json

@@ -0,0 +1,8 @@
+{
+  "$schema": "https://langgra.ph/schema.json",
+  "dependencies": ["."],
+  "env": {},
+  "graphs": {
+    "lead_agent": "src.agents:lead_agent"
+  }
+}

backend/pyproject.toml

@@ -0,0 +1,17 @@
+[project]
+name = "deer-flow"
+version = "0.1.0"
+description = "Add your description here"
+readme = "README.md"
+requires-python = ">=3.12"
+dependencies = [
+    "langchain>=1.2.3",
+    "langchain-deepseek>=1.0.1",
+    "langchain-openai>=1.1.7",
+    "langgraph>=1.0.6",
+    "markdownify>=1.2.2",
+    "pydantic>=2.12.5",
+    "pyyaml>=6.0.3",
+    "readabilipy>=0.3.0",
+    "tavily-python>=0.7.17",
+]