feat: add CLAP and FST indicators to score fusion results

app/services/score_fusion.py

@@ -322,6 +322,8 @@ def _build_indicators(
     confidence: float,
     features: AudioFeatures,
     vocals: Optional[VocalFeatures],
+    clap: Optional[_ExternalScore],
+    fst: Optional[_ExternalScore],
     ext_mai: Optional[_ExternalScore],
     ext_ses: Optional[_ExternalScore],
 ) -> List[str]:
@@ -348,38 +350,59 @@ def _build_indicators(
     # Feature-specific indicators
     if features.spectral_regularity > 0.7:
         indicators.append(
-            "Spectral patterns show high regularity typical of AI generation."
+            "Spectral patterns show high regularity "
+            "typical of AI generation."
         )
     elif features.spectral_regularity < 0.3:
         indicators.append(
-            "Spectral variation is consistent with natural human composition."
+            "Spectral variation is consistent with "
+            "natural human composition."
         )
 
     if features.temporal_patterns > 0.7:
         indicators.append(
             f"Temporal patterns are metronomically precise "
-            f"(tempo stability: {features.tempo_stability:.3f}s std)."
+            f"(tempo stability: "
+            f"{features.tempo_stability:.3f}s std)."
         )
     elif features.temporal_patterns < 0.3:
         indicators.append(
-            "Natural timing variation detected in rhythmic patterns."
+            "Natural timing variation detected in "
+            "rhythmic patterns."
         )
 
     if features.harmonic_structure > 0.7:
         indicators.append(
-            "Harmonic progressions follow predictable AI-typical patterns."
+            "Harmonic progressions follow predictable "
+            "AI-typical patterns."
         )
 
     # Vocal indicators
     if vocals and vocals.has_vocals:
         indicators.extend(vocals.indicators)
 
-    # External source indicators
+    # CLAP embedding indicator (Layer 2)
+    if clap and clap.available:
+        label = "AI-generated" if clap.is_ai else "human-composed"
+        indicators.append(
+            f"CLAP embedding analysis classified as {label} "
+            f"({clap.confidence:.1%} confidence)."
+        )
+
+    # FST indicator (Layer 3)
+    if fst and fst.available:
+        label = "AI-generated" if fst.is_ai else "human-composed"
+        indicators.append(
+            f"FST (Fusion Segment Transformer) classified as "
+            f"{label} ({fst.confidence:.1%} confidence)."
+        )
+
+    # Legacy external source indicators
     if ext_mai and ext_mai.available:
         label = "AI-generated" if ext_mai.is_ai else "human-composed"
         indicators.append(
-            f"External Music-AI detector classified as {label} "
-            f"({ext_mai.confidence:.1%} confidence)."
+            f"External Music-AI detector classified as "
+            f"{label} ({ext_mai.confidence:.1%} confidence)."
         )
 
     if ext_ses and ext_ses.available: