perf: array-based BFS in computeStress() — eliminates HashMap/boxing overhead - #124

buildx failed with: ERROR: failed to build: failed to solve: process "/bin/sh -c mkdir -p Gvisual/build/classes && find Gvisual/src -name '*.java' > Gvisual/sources.txt && javac -source 8 -target 8 -cp \"$(find Gvisual/lib -name '*.jar' -not -path '*/test/*' | tr '\\n' ':')\" -d Gvisual/build/classes @Gvisual/sources.txt" did not complete successfully: exit code: 1