feat(deploy): add Dockerfile.z3 multi-stage build with Z3 from source

deploy/Dockerfile.z3

@@ -0,0 +1,60 @@
+# Dockerfile.z3 — multi-stage build that compiles Z3 from source and
+# statically links it into a distroless-compatible symkerneld image.
+#
+# Usage:
+#   docker build -f deploy/Dockerfile.z3 -t symkerneld:z3 .
+#
+# Optional build args:
+#   Z3_VERSION     — Z3 git tag to build (default: z3-4.13.4)
+#   BUILD_Z3_FROM_SOURCE — set to "1" to compile Z3; omit to use apt package
+
+ARG GO_VERSION=1.24
+ARG Z3_VERSION=z3-4.13.4
+ARG BUILD_Z3_FROM_SOURCE=1
+
+# ── Stage 1: Z3 build ────────────────────────────────────────────────────────
+FROM debian:bookworm-slim AS z3-builder
+ARG Z3_VERSION
+ARG BUILD_Z3_FROM_SOURCE
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    git cmake python3 g++ make ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+RUN if [ "${BUILD_Z3_FROM_SOURCE}" = "1" ]; then \
+      git clone --depth 1 --branch "${Z3_VERSION}" \
+        https://github.com/Z3Prover/z3.git /z3-src && \
+      cmake -S /z3-src -B /z3-build \
+        -DCMAKE_BUILD_TYPE=Release \
+        -DZ3_BUILD_LIBZ3_SHARED=OFF \
+        -DCMAKE_INSTALL_PREFIX=/z3-install && \
+      cmake --build /z3-build --parallel $(nproc) && \
+      cmake --install /z3-build; \
+    else \
+      apt-get update && apt-get install -y --no-install-recommends z3 && \
+      mkdir -p /z3-install/bin && \
+      cp $(which z3) /z3-install/bin/z3; \
+    fi
+
+# ── Stage 2: Go build ────────────────────────────────────────────────────────
+FROM golang:${GO_VERSION}-bookworm AS go-builder
+
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -ldflags="-s -w" -o /symkerneld ./cmd/symkerneld
+
+# ── Stage 3: Runtime (distroless) ────────────────────────────────────────────
+FROM gcr.io/distroless/static-debian12:nonroot
+
+# Z3 binary from stage 1
+COPY --from=z3-builder /z3-install/bin/z3 /usr/local/bin/z3
+
+# symkerneld binary from stage 2
+COPY --from=go-builder /symkerneld /symkerneld
+
+EXPOSE 8080
+USER nonroot:nonroot
+ENTRYPOINT ["/symkerneld"]