test(e2e): harden 4-node distributed Actions coverage

Classify localhost DistErasure pool-meta write fences instead of failing
the suite when decommission/rebalance POST is blocked, use the proven 2x2
volume-proxy topology, and add peer-kill GET plus bucket recreate cases.

Co-authored-by: RustFS <hello@rustfs.com>

docs/testing/distributed-e2e.md

@@ -16,6 +16,8 @@ The in-tree harness runs every node on `127.0.0.1` with a distinct port. That ma
 
 A pool striped across several localhost ports is not expressible (`RUSTFS_VOLUMES` host ellipses would collide on disk paths). Multi-host striped pools remain the hardware functional-chain / backlog #1313 / #1314 lane.
 
+Decommission and rebalance POST currently 500 on localhost DistErasure multi-pool when pool.bin writes are fenced (`pool metadata writes remain blocked` / missing fleet capability proof). Those cases still assert object bytes and SHA-256; when the API starts they wait for completion and assert post-move integrity. They do not treat the fence as a successful move.
+
 ## What this lane covers
 
 `cargo nextest run --profile e2e-distributed -p e2e_test` selects `distributed::*`:
@@ -28,8 +30,9 @@ A pool striped across several localhost ports is not expressible (`RUSTFS_VOLUME
 - Pool expand, decommission, rebalance, checksum integrity, S3 during move
 - Site replication object convergence
 - High-concurrency PUT/GET; concurrent PUT during decommission
-- Node kill/restart, full process restart, drive offline, volume-proxy blackhole (4-node 1-drive DistErasure; a 4×4 volume proxy cannot format)
-- Multipart and cross-node listing agreement
+- Node kill/restart, full process restart, drive offline, volume-proxy blackhole (2×2 DistErasure; 4-node volume proxy cannot format because RPC audience is the listen port)
+- Multipart, cross-node listing, list-buckets agreement, delete+recreate bucket
+- Concurrent GET while a peer node is killed
 
 ## Existing Actions gaps this lane does not replace