Parses constraints of the form a x + b y ≤ c or ≥ (we convert ≥ to ≤ by
multiplying both sides by −1).
Automatically adds non-negativity (x ≥ 0, y ≥ 0) if toggled.
Computes all pairwise intersections of constraint lines (including axes if applicable), filters feasible
points, and evaluates the objective at those candidate vertices.
Reports the optimal point and value for Max/Min, or indicates if the model is infeasible or likely
unbounded.