Initial implementation: host lifecycle + PXE + admin dashboard

Go service for Proxmox homelab cluster provisioning. Handles PXE boot,
Proxmox autoinstall (answer file generation), cluster join via SSH,
and Infrastructure API registration.

- Host state machine (registered → pxe_ready → installing → ready)
- dnsmasq supervisor with MAC-based allowlist
- iPXE script and Proxmox answer file generation
- First-boot phone-home → cluster join → infra registration
- Operation locking with expiry (409 on conflict)
- SSE event hub for real-time dashboard updates
- Admin dashboard (host grid, detail, registration form)
- Config-driven server types with hot-reload
- Docker deployment (multi-stage fat image)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

deploy/Dockerfile

@@ -0,0 +1,28 @@
+FROM golang:1.23-bookworm AS builder
+
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -o /provisioning ./cmd/provisioning
+
+FROM debian:bookworm-slim
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    dnsmasq \
+    openssh-client \
+    ipxe \
+    ca-certificates \
+    dmidecode \
+    curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY --from=builder /provisioning /usr/local/bin/provisioning
+
+RUN mkdir -p /data /etc/provisioning/keys
+
+EXPOSE 8080
+VOLUME ["/data", "/etc/provisioning"]
+
+ENTRYPOINT ["/usr/local/bin/provisioning"]
+CMD ["-config", "/etc/provisioning/provisioning.yaml"]