Simulate with Random Input

Simulate the LIF neuron with Gaussian input noise and plot V(t).

Your task:
1. Use i_std = 0.5e-11 and np.random.seed(2024)
2. Replace sinusoidal current with:
   i_t = i_mean + i_std * np.random.normal() * np.sqrt(dt)
3. Run full simulation, store t_list and v_list
4. Plot V(t) with threshold line at y=-50 mV

The resulting spike times should look irregular — that's the noise!