Renamed 28 files to short, single-concept names matching avalanchego's
convention; dropped the noise tokens quorum_/red_/zz_/_gate_/_guard_/
_regression_/_harness_/_probe_/_addition_/_propagation_/_tracking_/
_convergence_/_edge_cases_/configurations. Source: cert.go cert_codec.go
quasar.go topology.go guard.go (was quorum_*). Tests: accept/block/catchup/
params/errors/fetch/poll/proposer/dynamic/finality/height/stake/status/sync/
reorg/weighted/probe + epoch_{binding,receive,finality}_test.go + helpers_test.go.
Stale file-header references updated to the new names. Pure cosmetic — same
package, no symbol changes.
Green: CGO_ENABLED=0 go test -count=1 ./engine/chain/ ok (27.4s).
