The URL test history update hook and the Clash mode update hook were
single-slot: the API service's attached service overwrote the hook set
by the daemon, so clients stopped receiving group updates. Replace both
with multicast hook lists.
Also share a single URL test history storage via context: Clash API
looked it up under a key nobody registered and fell back to its own
empty storage, so dashboards showed no delay once an API service was
configured. Selector changes now notify through the shared storage,
covering selections made from any API surface.
