fix(queueingmodel): propagate explicit SLO targets from default conf

[asm582]

After this fix:

INFO    saturation/engine_queueing_model.go:132
Queueing model analysis completed {"modelID": "Qwen/Qwen3-0.6B", "totalSupply": 0, "totalDemand": 0, "utilization": 0, "requiredCapacity": 0, "spareCapacity": 0}