Compute function purity annotations

[aymannadeem]

Function purity means that the function in question has no side effects (e.g. does not modify global state, perform I/O, or mutate input). It also implies the function is deterministic: same output for the same input.

There are two main approaches to checking function purity:

1. Static analysis (No execution, purely code inspection)
2. LLM-based Analysis (Using AI to infer purity)

I need to investigate the easiest/most feasible implementation approaches and decide on which one we want to pursue.