feat: add multi-agents template based on workflows (#271)

.changeset/tall-ties-own.md

e2e/multiagent_template.spec.ts

helpers/run-app.ts

helpers/typescript.ts

questions.ts

templates/types/multiagent/fastapi/README-template.md

templates/types/multiagent/fastapi/app/agents/dummy/agent.py

templates/types/multiagent/fastapi/app/agents/multi.py

templates/types/multiagent/fastapi/app/agents/planner.py

templates/types/multiagent/fastapi/app/agents/single.py

templates/types/multiagent/fastapi/app/api/__init__.py

...ates/types/multiagent/fastapi/app/api/routers/__init__.py

templates/types/multiagent/fastapi/app/api/routers/chat.py

...s/types/multiagent/fastapi/app/api/routers/chat_config.py

templates/types/multiagent/fastapi/app/api/routers/models.py

templates/types/multiagent/fastapi/app/api/routers/upload.py

...pes/multiagent/fastapi/app/api/routers/vercel_response.py

templates/types/multiagent/fastapi/app/api/services/file.py

...s/types/multiagent/fastapi/app/api/services/suggestion.py

templates/types/multiagent/fastapi/app/config.py