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/pyproject.toml

@@ -0,0 +1,35 @@
+[build-system]
+requires = ["setuptools>=68.0"]
+build-backend = "setuptools.build_meta"
+
+[project]
+name = "kb-engine"
+version = "2.0.0"
+description = "Knowledge base engine — FastAPI server with hybrid search and async ingestion"
+requires-python = ">=3.11"
+license = "MIT"
+dependencies = [
+    "fastapi>=0.115",
+    "uvicorn[standard]>=0.30",
+    "python-multipart>=0.0.9",
+    "click>=8.1",
+    "pyyaml>=6.0",
+    "sentence-transformers>=3.0",
+    "sqlite-vec>=0.1.1",
+    "docling>=2.0",
+]
+
+[project.optional-dependencies]
+dev = [
+    "pytest>=8.0",
+    "pytest-asyncio>=0.24",
+    "httpx>=0.27",
+]
+
+[tool.setuptools.packages.find]
+where = ["."]
+include = ["kb*"]
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+asyncio_mode = "auto"