feat: switch away from websocket to stdout messaging for agent

Dockerfile

@@ -1,3 +1,15 @@
+FROM golang:1.24 AS agent-build
+WORKDIR /app
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY agent/ ./agent
+RUN CGO_ENABLED=0 GOOS=linux go build \
+	-trimpath \
+	-ldflags "-s -w" \
+	-o /app/hp_agent ./agent/cmd/hp_agent
+
 FROM node:22-alpine AS build
 WORKDIR /app
 
@@ -11,8 +23,12 @@ COPY . .
 RUN pnpm run build
 
 FROM node:22-alpine
+RUN apk add --no-cache ca-certificates
 RUN mkdir -p /var/lib/headplane
+RUN mkdir -p /usr/libexec/headplane
 
 WORKDIR /app
 COPY --from=build /app/build /app/build
+COPY --from=agent-build /app/hp_agent /usr/libexec/headplane/agent
+RUN chmod +x /usr/libexec/headplane/agent
 CMD [ "node", "./build/server/index.js" ]