fix: PhysicalFeatureExtractor 除零保护 — np.sign(0)=0 导致 inf

- 分母保护 np.sign(x)*1e-12 在 x=0 时变为 0，a/0 → inf
- 改为固定 1e-12 兜底 + nan_to_num + clip 安全阀
- 同时修复 ratio 型和 ratio_single 型两处

src/preprocessing/spectral_Preprocessing.py

@@ -502,12 +502,15 @@ class PhysicalFeatureExtractor(TransformerMixin, BaseEstimator, _ArrayAsFloat64)
             a = X[:, ia]; b = X[:, ib]
             if ftype == 'ratio':
                 denom = a + b
-                denom = np.where(np.abs(denom) < 1e-12, np.sign(denom) * 1e-12, denom)
+                denom = np.where(np.abs(denom) < 1e-12, 1e-12, denom)
                 feats.append(((a - b) / denom).reshape(-1, 1))
             else:  # ratio_single
-                denom = np.where(np.abs(b) < 1e-12, np.sign(b) * 1e-12, b)
+                denom = np.where(np.abs(b) < 1e-12, 1e-12, b)
                 feats.append((a / denom).reshape(-1, 1))
-        return np.hstack(feats)
+        out = np.hstack(feats)
+        out = np.nan_to_num(out, nan=0.0, posinf=0.0, neginf=0.0)
+        out = np.clip(out, -1e15, 1e15)
+        return out
 
 
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