Fix container name handling for hyphenated service names

Extract ContainerNameFor and SplitContainerName into names.go.
ContainerNameFor handles single-component services where service
name equals component name (e.g., mc-proxy → "mc-proxy" not
"mc-proxy-mc-proxy"). SplitContainerName checks known services
from the registry before falling back to naive split on "-", fixing
mc-proxy being misidentified as service "mc" component "proxy".

Also fixes podman ps JSON parsing (Command field is []string not
string) found during deployment.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/runtime/podman.go

@@ -179,7 +179,7 @@ type podmanPSEntry struct {
 	Names   []string `json:"Names"`
 	Image   string   `json:"Image"`
 	State   string   `json:"State"`
-	Command string   `json:"Command"`
+	Command []string `json:"Command"`
 }
 
 // List returns information about all containers.