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/DOCKER_ARCHIVE_INSTRUCTIONS.md

@@ -0,0 +1,77 @@
+# Docker Image Archive Instructions
+
+## Build Stage Archive Strategy
+
+The multi-stage Dockerfile creates two images:
+1. **Builder stage** (`soprano_to_rvc-rvc:builder`) - Contains all build tools and compiled dependencies (~85GB)
+2. **Runtime stage** (`soprano_to_rvc-rvc:latest`) - Minimal runtime image (~15-20GB target)
+
+### After Build Completes
+
+Archive the builder stage to `/4TB/Docker/` for future reuse:
+
+```bash
+# 1. Tag the builder stage (it's created during multi-stage build)
+docker tag $(docker images -q --filter "label=stage=builder" soprano_to_rvc-rvc) soprano_to_rvc-rvc:builder
+
+# 2. Save the builder image to archive
+mkdir -p /4TB/Docker
+docker save soprano_to_rvc-rvc:builder | gzip > /4TB/Docker/soprano-rvc-builder-rocm6.4-pytorch2.5.1.tar.gz
+
+# 3. Verify the archive
+ls -lh /4TB/Docker/soprano-rvc-builder-rocm6.4-pytorch2.5.1.tar.gz
+
+# 4. Check final runtime image size
+docker images soprano_to_rvc-rvc:latest
+```
+
+### To Restore Builder from Archive
+
+If you need to rebuild or modify dependencies later:
+
+```bash
+# Load the archived builder image
+docker load < /4TB/Docker/soprano-rvc-builder-rocm6.4-pytorch2.5.1.tar.gz
+
+# Use it as a base for modifications
+docker run --rm -it soprano_to_rvc-rvc:builder bash
+```
+
+### Size Comparison
+
+**Before (single-stage):**
+- Image: `soprano_to_rvc-rvc:latest` = 85.7 GB
+
+**After (multi-stage):**
+- Builder (archived): ~50-60 GB (compressed to ~20-25 GB)
+- Runtime: ~15-20 GB
+- **Savings: ~65-70 GB on runtime image**
+
+### What's Removed from Runtime
+
+The runtime stage excludes:
+- Build tools (gcc, g++, make, cmake)
+- Development headers
+- Git repositories
+- pip cache
+- Intermediate compilation artifacts
+- Unused conda packages
+
+### What's Kept in Runtime
+
+The runtime stage includes:
+- ROCm libraries (required for GPU)
+- PyTorch 2.5.1+rocm6.4
+- All Python packages from requirements-rvc.txt
+- RVC models and application code
+- Minimal system libraries (ffmpeg, libsndfile, curl)
+
+## Archive Metadata
+
+**Created:** 2026-01-15
+**Base Image:** rocm/pytorch:rocm6.4_ubuntu22.04_py3.10_pytorch_release_2.5.1
+**PyTorch Version:** 2.5.1+rocm6.4
+**ROCm Version:** 6.4
+**Python Version:** 3.10.x
+**Target GPU:** AMD RX 6800 (gfx1030)
+**Key Fix:** Apex removed (incompatible C++ extensions)