add: absorb soprano_to_rvc as regular subdirectory

Voice conversion pipeline (Soprano TTS → RVC) with Docker support.
Previously tracked as bare gitlink; removed .git/ directories and
absorbed into main repo for unified tracking.

Includes: Soprano TTS, RVC WebUI integration, Docker configs,
WebSocket API, and benchmark scripts.
Updated .gitignore to exclude large model weights (*.pth, *.pt, *.onnx, *.index).
287 files (3.1GB of ML weights properly excluded via gitignore).

soprano_to_rvc/start_docker.sh

@@ -0,0 +1,73 @@
+#!/bin/bash
+# Quick start script for Soprano + RVC Docker services
+
+set -e
+
+cd "$(dirname "$0")"
+
+echo "🎤 Starting Soprano + RVC Services"
+echo "===================================="
+echo ""
+
+# Check if containers exist
+if ! docker-compose ps | grep -q "soprano"; then
+    echo "⚠️  Containers not built yet. Building now..."
+    ./build_docker.sh
+fi
+
+# Start services
+echo "🚀 Starting services..."
+docker-compose up -d
+
+echo ""
+echo "⏳ Waiting for services to be ready..."
+echo "   (This may take 60-120 seconds for model loading)"
+echo ""
+
+# Wait for health checks
+MAX_WAIT=180
+WAITED=0
+
+while [ $WAITED -lt $MAX_WAIT ]; do
+    if curl -f -s http://localhost:8765/health > /dev/null 2>&1; then
+        echo ""
+        echo "✅ Services are ready!"
+        
+        # Show health status
+        echo ""
+        echo "📊 Health Status:"
+        curl -s http://localhost:8765/health | python3 -m json.tool || echo "  (Health check passed but response not JSON)"
+        
+        echo ""
+        echo "🎵 Service is ready to use!"
+        echo ""
+        echo "Try it out:"
+        echo "  curl -X POST http://localhost:8765/api/speak \\"
+        echo "       -H 'Content-Type: application/json' \\"
+        echo "       -d '{\"text\": \"Hello, I am Miku!\"}' \\"
+        echo "       -o test.wav"
+        echo ""
+        echo "View logs:"
+        echo "  docker-compose logs -f"
+        echo ""
+        echo "Stop services:"
+        echo "  docker-compose down"
+        exit 0
+    fi
+    
+    echo -n "."
+    sleep 5
+    WAITED=$((WAITED + 5))
+done
+
+echo ""
+echo "❌ Services did not become ready within ${MAX_WAIT} seconds"
+echo ""
+echo "Check logs for errors:"
+echo "  docker-compose logs soprano"
+echo "  docker-compose logs rvc"
+echo ""
+echo "Check container status:"
+echo "  docker-compose ps"
+
+exit 1