replace ContainerRuntime CLI to Bollard crate (default: docker socket)

limit tool result to open router tool response (with truncated info for
ai)

Hard kill if graceful shutdown is too long

Containerfile

@@ -1,4 +1,4 @@
-FROM rust:1.97-trixie as builder
+FROM rust:1.98-trixie as builder
 
 WORKDIR /app
 
@@ -10,6 +10,33 @@ RUN cargo build --release --package herald-server
 
 FROM debian:trixie-slim
 
+# git clones the pull request. ca-certificates is what every HTTPS call needs
+# (Gitea, OpenRouter, git). The shared libraries are the non-base ones the binary
+# links against, as reported by `ldd target/release/herald-server`; libc, libm
+# and libgcc_s come from the base image.
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    ca-certificates \
+    git \
+    libssl3t64 \
+    libzstd1 \
+    zlib1g \
+    && rm -rf /var/lib/apt/lists/*
+
+# Herald drives the container daemon through its socket (DOCKER_HOST, default
+# unix:///var/run/docker.sock), so neither docker nor podman is needed here: the
+# compose file mounts the socket. Reaching that socket is what this user needs,
+# and the socket is root-equivalent, so either run the container as root or give
+# it the socket's group, e.g. `group_add: ["<gid of the host docker group>"]`.
+RUN useradd --create-home --shell /usr/sbin/nologin --uid 10001 herald
+
 WORKDIR /app
-COPY --from=builder /app/target/release/herald-server .
-CMD [ "./herald-server" ]
+COPY --from=builder /app/target/release/herald-server ./herald-server
+
+# git looks for its configuration under $HOME.
+ENV HOME=/home/herald
+
+USER herald
+
+# Exec form, so the binary is PID 1 and receives the SIGTERM it handles to shut
+# down gracefully.
+CMD ["./herald-server"]