AI PoC workaround-for-stack-overflow reworks [do not merge]

[MOZGIII]

This is a quickly drafted branch with AI tooling assisted PoC for the stack overflow issue. Good for quick tryouts, but we probably shouldn't merge it (at least as-is).

---

The idea is unwind the recursion into a manually managed stack to avoid being limited by the system thread's stack size.

Use commit filtering on Github to review - the first two commits just move the tests out of Ctrl+F scope so it's possible to navigate the code quickly and find fn uses manually.

[github-actions]

Coverage Report

Python Coverage Metric Coverage Lines 75.8% Branches 57.8% Download HTML Report

Rust Coverage Metric Coverage Lines 59.1% 🔴 (-0.9%) Branches N/A Download HTML Report

_{Compared to main branch}