tac: add tacchaind pruned compose for mainnet and spb

Source-build Dockerfile (tacchain v1.6.0), init script with statesync via
cometbft-common.sh, EVM RPC/WS on 8545/8546, and dshackle slugs tac/tac-spb.

tac/tacchaind.Dockerfile

@@ -0,0 +1,35 @@
+# tacchaind — source build mirroring upstream TacBuild/tacchain Dockerfile (v1.6.0).
+ARG VERSION=v1.6.0
+
+FROM golang:1.23.8-alpine3.21 AS go-builder
+
+RUN apk add --no-cache \
+    ca-certificates \
+    build-base \
+    libusb-dev \
+    linux-headers \
+    eudev-dev
+
+WORKDIR /code
+RUN git clone https://github.com/TacBuild/tacchain.git /code && \
+    cd /code && \
+    git checkout "${VERSION}" && \
+    LEDGER_ENABLED=true make build
+
+FROM alpine:3.21
+
+RUN apk upgrade --no-cache && \
+    apk add --no-cache \
+    ca-certificates \
+    libusb
+
+COPY --from=go-builder /code/build/tacchaind /usr/bin/tacchaind
+COPY ./scripts/cometbft-common.sh /usr/local/bin/cometbft-common.sh
+COPY ./scripts/init.sh /usr/local/bin/init.sh
+RUN chmod +x /usr/local/bin/init.sh /usr/local/bin/cometbft-common.sh
+
+WORKDIR /opt
+
+EXPOSE 1317 26656 26657
+
+ENTRYPOINT ["init.sh"]