refactor: use uv for dependency management

backend/pyproject.toml

@@ -0,0 +1,31 @@
+[project]
+name = "insightflow-backend"
+version = "0.3.0"
+description = "InsightFlow Backend - Knowledge Graph Platform"
+requires-python = ">=3.11"
+dependencies = [
+    "fastapi>=0.115.0",
+    "uvicorn[standard]>=0.32.0",
+    "python-multipart>=0.0.17",
+    "oss2>=2.18.6",
+    "alibabacloud-tea-openapi>=0.3.12",
+    "alibabacloud-tingwu20230930>=2.0.2",
+    "httpx>=0.27.2",
+    "pydantic>=2.9.2",
+    "python-dotenv>=1.0.1",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0.0",
+    "black>=24.0.0",
+    "ruff>=0.3.0",
+]
+
+[tool.black]
+line-length = 100
+target-version = ['py311']
+
+[tool.ruff]
+line-length = 100
+select = ["E", "F", "I"]