feat: add Docker support

This commit adds Docker support to goose via a multi-stage Dockerfile that:
- Uses rust:1.75 for building
- Uses debian:bookworm-slim for runtime
- Includes required system dependencies
- Provides documentation for Docker usage

The Docker image allows running goose without installing Rust locally and
provides a consistent runtime environment.

Dockerfile

@@ -0,0 +1,33 @@
+# Build stage
+FROM rust:1.84 AS builder
+
+WORKDIR /usr/src/goose
+
+# Copy only the files needed for building
+COPY Cargo.toml ./
+COPY crates ./crates
+
+# Install minimal build dependenciesd
+RUN apt-get update && \
+    apt-get install -y pkg-config libssl-dev libdbus-1-dev && \
+    rm -rf /var/lib/apt/lists/*
+
+# Build the binary
+RUN cargo build --release
+
+# Runtime stage
+FROM debian:bookworm-slim
+
+WORKDIR /app
+
+# Install minimal runtime dependencies
+RUN apt-get update && \
+    apt-get install -y libssl3 ca-certificates libxcb1 libdbus-1-3 && \
+    rm -rf /var/lib/apt/lists/*
+
+# Copy the binary from builder
+COPY --from=builder /usr/src/goose/target/release/goose /app/goose
+
+ENV GOOSE_KEYRING_BACKEND=file
+
+CMD ["/app/goose"]