v2 restructure: Go client, Docker engine, release tooling

- Remove v1 Python CLI (src/kb_search/, tests/, root pyproject.toml, uv.lock, .venv)
- Add Go client with cross-platform build (client/)
- Add FastAPI engine with NVIDIA and multi-stage ROCm Dockerfiles (engine/)
- Add VERSION files for client and engine, wired into builds
- Add release.sh for automated build, tag, release, and Docker push
- Update README with build/release docs and ROCm migration note
- Clean up .gitignore for v2 project structure

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

engine/Dockerfile.rocm

@@ -0,0 +1,68 @@
+# Stage 1: Build — install Python deps with dev tools available
+FROM rocm/dev-ubuntu-24.04:6.4-complete AS builder
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    python3.12 python3.12-venv python3.12-dev python3-pip \
+    libpoppler-cpp-dev poppler-utils \
+    build-essential curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=ghcr.io/astral-sh/uv:latest /uv /usr/local/bin/uv
+
+WORKDIR /app
+
+COPY pyproject.toml ./
+COPY kb/ kb/
+COPY main.py ./
+COPY VERSION ./
+
+RUN uv venv .venv && \
+    . .venv/bin/activate && \
+    uv pip install -e . && \
+    uv pip install --no-deps onnxruntime-rocm
+
+# Stage 2: Runtime — minimal ROCm runtime libs only
+FROM ubuntu:24.04
+
+ENV DEBIAN_FRONTEND=noninteractive
+
+# Add ROCm apt repository
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    ca-certificates curl gnupg \
+    && mkdir -p /etc/apt/keyrings \
+    && curl -fsSL https://repo.radeon.com/rocm/rocm.gpg.key \
+       | gpg --dearmor -o /etc/apt/keyrings/rocm.gpg \
+    && echo "deb [arch=amd64 signed-by=/etc/apt/keyrings/rocm.gpg] https://repo.radeon.com/rocm/apt/6.4.1 noble main" \
+       > /etc/apt/sources.list.d/rocm.list \
+    && printf 'Package: *\nPin: release o=repo.radeon.com\nPin-Priority: 600\n' \
+       > /etc/apt/preferences.d/rocm-pin-600 \
+    && apt-get update && apt-get install -y --no-install-recommends \
+    python3.12 python3.12-venv \
+    libpoppler-cpp0t64 poppler-utils \
+    libgl1 libglib2.0-0 \
+    rocm-hip-runtime \
+    rocm-hip-libraries \
+    miopen-hip \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /app
+
+# Copy built venv and application from builder
+COPY --from=builder /app/.venv .venv
+COPY --from=builder /app/kb kb
+COPY --from=builder /app/main.py .
+COPY --from=builder /app/pyproject.toml .
+COPY --from=builder /app/VERSION .
+
+ENV PATH="/app/.venv/bin:$PATH"
+ENV VIRTUAL_ENV="/app/.venv"
+ENV KB_DEVICE=auto
+ENV KB_INGEST_DEVICE=auto
+ENV KB_DATA_DIR=/data
+
+EXPOSE 8000
+VOLUME ["/data"]
+
+CMD ["uvicorn", "main:app", "--host", "0.0.0.0", "--port", "8000"]