modify the application startup section & Readme

### Description of the bug:

It is recommended to modify the application startup section in the Makefile as shown below; otherwise, the application can only be accessed from the local machine.

Also, please note this in the README: if the application is accessed from a non-local machine, the backend API address in the frontend file App.tsx must be updated accordingly.

(1) Startup section in the file Makefile

Suggested modification

dev-frontend:
@echo "Starting frontend development server..."
@cd frontend && npm run dev -- --host 0.0.0.0 --port 5173

dev-backend:
@echo "Starting backend development server..."
@cd backend && langgraph dev --host 0.0.0.0 --port 2024

(2) Backend API address in the frontend file App.tsx

apiUrl: import.meta.env.DEV
? "http://deployMachineIP:2024"
: "http://deployMachineIP:8123"

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Actual vs expected behavior

No response

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Any other information you’d like to share?

No response