The /topologies/{id}/events SSE proxy now subscribes to two bus
patterns concurrently and merges them through a bounded asyncio.Queue:
* topology.{id}.> — lifecycle (status, mutation.*) — unchanged.
* decky.> — per-decky events, filtered by payload.topology_id
so a fleet decky sharing a name with a topology
decky doesn't leak across.
_sse_name_for routes 'decky.<name>.service.added' to the SSE event
name 'decky.service.added' (kept the prefix so the frontend doesn't
collide with topology lifecycle events that share leaf names like
'status').
useTopologyStream surfaces the two new event names; MazeNET.tsx's
onStreamEvent optimistically patches the matching node's services
list so a second tab reflects shape changes without a refetch.
Adds a fleet_singletons array to ServiceCatalogResponse so per-decky
add UIs can filter out services like LLMNR that run once fleet-wide
(and would 422 server-side at the live add endpoint).
The existing 'services: list[str]' field is unchanged for back-compat
with MazeNET/useMazeApi.ts:257; the new field is additive.
decnet_web/src/hooks/useServiceRegistry.ts wraps the endpoint with a
module-scoped cache (registry only changes on BYOS install / plugin
drop, neither of which happens mid-session) and exposes a precomputed
.perDecky list so consumers don't need to re-derive the diff.
