Bus topic segments are NATS-style tokens and the validator at
bus/topics.py:402 rejects '.', '*', '>', whitespace. My W3 constants
'service.added' / 'service.removed' tripped this on every live
add/remove call:
ValueError: topic segment 'service.added' may not contain '.', ...
Renamed both to underscore form: DECKY_SERVICE_ADDED = 'service_added'.
Aligned the SSE forwarder's name mapping (decky.<name>.service_added →
SSE event 'decky.service_added') and the frontend's
useTopologyStream listener + MazeNET.tsx event handler. Also updated
the wiki entry with a note about the underscore.