feat: add local-test skill and Dockerfile.test for web gateway testing (#524)

Add Dockerfile.test as reusable infrastructure for spinning up local
test instances with libsql (no PostgreSQL dependency). Defaults to
port 3003 to avoid conflict with dev server.

Add local-test workspace skill that teaches the agent how to build,
run, and test against local Docker containers using Chrome MCP browser
automation tools. Covers LLM backend configuration, multi-instance
testing, cleanup, and troubleshooting.

Dockerfile.test

@@ -0,0 +1,57 @@
+# Lightweight test Dockerfile for IronClaw web gateway testing.
+#
+# Build:
+#   docker build --platform linux/amd64 -f Dockerfile.test -t ironclaw-test .
+#
+# Run (each on a different port):
+#   docker run --rm -p 3003:3003 ironclaw-test
+#   docker run --rm -p 3004:3003 ironclaw-test
+#   docker run --rm -p 3005:3003 ironclaw-test
+
+# Stage 1: Build (libsql only — no PostgreSQL dependency)
+FROM rust:1.92-slim-bookworm AS builder
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    pkg-config libssl-dev cmake gcc g++ \
+    && rm -rf /var/lib/apt/lists/* \
+    && rustup target add wasm32-wasip2 \
+    && cargo install wasm-tools
+
+WORKDIR /app
+
+COPY Cargo.toml Cargo.lock ./
+COPY build.rs build.rs
+COPY src/ src/
+COPY tests/ tests/
+COPY migrations/ migrations/
+COPY registry/ registry/
+COPY channels-src/ channels-src/
+COPY wit/ wit/
+
+RUN cargo build --release --no-default-features --features libsql --bin ironclaw
+
+# Stage 2: Runtime
+FROM debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    ca-certificates libssl3 \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=builder /app/target/release/ironclaw /usr/local/bin/ironclaw
+
+RUN useradd -m -u 1000 -s /bin/bash ironclaw
+USER ironclaw
+WORKDIR /home/ironclaw
+
+EXPOSE 3003
+
+ENV RUST_LOG=ironclaw=info \
+    GATEWAY_ENABLED=true \
+    GATEWAY_HOST=0.0.0.0 \
+    GATEWAY_PORT=3003 \
+    GATEWAY_AUTH_TOKEN=test \
+    DATABASE_BACKEND=libsql \
+    LIBSQL_PATH=/home/ironclaw/test.db \
+    SANDBOX_ENABLED=false
+
+ENTRYPOINT ["ironclaw", "--no-onboard"]