Topological Sort (Cell Dependencies)

Question

## Problem

Cells form a dependency graph (A depends on B). Given dependencies, compute a valid recompute order; detect cycles.

## Example
```
A->B, B->C => recompute C,B,A; A->B,B->A -> cycle
```

## Constraints
- Up to 10^4 cells

## What Airtable looks for
Core to Airtable's formula engine. Kahn's algorithm + cycle detection. Reported theme.