D3 — Analytic placement, then annealing, then exact windows

Decision

Analytic global placement, then SA/LNS, then CP-SAT windows

Alternatives

SA only (SA-PCB); GA only (Allegro X AI); RL (RL_PCB)

Reason

Analytic gives a provable relaxed optimum and a strong start; SA handles discrete PCB moves; CP-SAT gives exact local optima