Experimental: a particle that leaves the domain through a removing boundary face now ends its search as EXITED and is reported separately from a search failure.
- search_metrics.csv and Particle_Metrics.log add exited, exited_cumulative and exited_psi_sum. lost and lost_psi_sum now count only search failures.
- picurv summarize reports the exited counts.
- Settlement no longer searches a lost or exited particle again in later passes. Before, each loss was counted once per pass, and on curved boundaries a departed particle could migrate between ranks until the run aborted with "Particle migration failed to converge after 50 passes".
- A walk from a particle's previous cell that ends more than three cells beyond the boundary is treated as blocked and searched again from scratch in the same pass.