Override leaves whose backing MCP tool isn't actually deployed rendered in
`dws <svc> --help` but failed at invocation with "tool not found" (43 phantom
commands across 391 overrides; attendance declared 38, only 4 deployed).
BuildDynamicCommands now takes an existingTools oracle (CLI slug -> live tool
set from the tools/ cache). A leaf whose tool is missing from its resolved
server's set is marked Hidden; groups left childless collapse. Safety rails:
acts only when a server's tool set is KNOWN and non-empty (cold cache / overlay
/ plugin paths pass nil and no-op, never blanking the tree); serverOverride
leaves resolve against the target server; pipeline leaves are never hidden.
Adds scripts/dev/check-phantom-overrides.py as a publish-time gate, and
phantom_guard_test.go covering hide / cold-cache-keep / serverOverride / pipeline
/ empty-group-collapse.
修雨