🔧 SA3 杂音修复对比 — euler/50步 vs lcm/8步

根因：SA3 Medium 不是 LCM 蒸馏模型，错误的 lcm/8步/cfg=1 导致欠采样噪声

✅ 根因 & 修复

根因： stable_audio_3_medium.safetensors 是完整 FLOW 模型（非 LCM 蒸馏），但原参数用了 lcm/8步/cfg=1 → 严重欠采样 → 输出杂音。
修复： 改为 euler/50步/cfg=7.0/simple，同时保留 ConditioningStableAudio 修复 seconds_total bug。
已更新 KAP 路由默认参数。

Whoosh SFX (杂音版 ❌) lcm/8步/cfg=1
cinematic whoosh, air swoosh...
Whoosh SFX (修复后) euler/50步/cfg=7
cinematic whoosh, air swoosh, transition sound effect
Door Slam SFX euler/50步/cfg=7
heavy metal door slam, deep impact, reverb tail, industrial
Rain Ambient (10s) euler/50步/cfg=7
gentle rain on a tin roof, continuous, ambient, peaceful
Guitar One-shot euler/50步/cfg=7
electric guitar power chord, distorted, sustained, rock