[Vonng]

Problem

Availability-optimized writes can leave a readable null version across separate EC groups when a disk is unavailable. The all-version listing path used by ListObjectVersions, decommission, and rebalance only re-counted this case for latest-only reads, so a readable object could disappear from version listings and from migration after complete source-pool removal.

Change

• Recount ordinary null versions across modern EC groups for non-strict all-version reads as well.
• Add end-to-end coverage for unversioned and suspended buckets.
• Add a complete source-pool decommission, removal, restart, GET, LIST, and ListObjectVersions regression test.
• Run the new listing tests in CI's race-detector listing job.

Validation

• go test ./... -count=1
• CGO_ENABLED=0 go test ./cmd/ -count=1 -timeout 30m
• go test ./cmd -shuffle=on -count=1
• Focused race tests and repeated focused runs
• go vet ./cmd
• make verifiers
• make build
• git diff --check