fix(ci): change Docker Hub namespace from pezkuwichain/ to pezkuwi/

Docker Hub personal account namespace must match the username.
Updated all docker.io image references across workflows, actions,
docker-compose files, and zombienet configs.

pezcumulus/zombienet/examples/small_network.toml

@@ -1,5 +1,5 @@
 [relaychain]
-default_image = "pezkuwichain/pezkuwi:latest"
+default_image = "pezkuwi/pezkuwi:latest"
 default_command = "pezkuwi"
 chain = "pezkuwichain-local"
 
@@ -20,6 +20,6 @@ chain = "asset-hub-pezkuwichain-local"
 [[teyrchains.collators]]
 name = "charlie"
 validator = true
-image = "pezkuwichain/pezkuwi-teyrchain:latest"
+image = "pezkuwi/pezkuwi-teyrchain:latest"
 command = "pezkuwi-teyrchain"
 args = ["--force-authoring"]