fix(tracing): sweep .tmp.* trace files even when maxFiles is 0 (unlimited)

[anandgupta42]

Found during v0.8.1 release review (Chaos Gremlin, P3). Pre-existing.

FileExporter only sweeps leftover .tmp.* snapshot files via pruneOldTraces when maxFiles > 0 (default 100, so the common path is fine). With maxFiles: 0 ('unlimited'), repeated crashes can slowly accumulate .tmp.* files under the user-private data dir. Run the tmp sweep unconditionally, independent of maxFiles.