Add posthog to studio.shipsec.ai

We want to add analytics to studio.shipsec.ai .
Also enable `surveys` in posthog, as we would like to know user's feedback when this goes in public beta.

<img width="860" height="502" alt="Image" src="https://github.com/user-attachments/assets/618ec79e-aae7-4dfa-b0b0-3570aa370a2a" />