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>

internal/statemachine/host_test.go

@@ -0,0 +1,67 @@
+package statemachine
+
+import (
+	"testing"
+
+	"provisioning/internal/model"
+)
+
+func TestValidTransitions(t *testing.T) {
+	cases := []struct {
+		from    model.HostState
+		trigger Trigger
+		want    model.HostState
+	}{
+		{model.StateRegistered, TriggerRebuildRequested, model.StatePXEReady},
+		{model.StateReady, TriggerRebuildRequested, model.StatePXEReady},
+		{model.StateFailed, TriggerRebuildRequested, model.StatePXEReady},
+		{model.StatePXEReady, TriggerPXEScriptServed, model.StatePXEBooted},
+		{model.StatePXEBooted, TriggerAnswerServed, model.StateInstalling},
+		{model.StateInstalling, TriggerInstallWebhook, model.StateInstalled},
+		{model.StateInstalled, TriggerPhoneHome, model.StateFirstBoot},
+		{model.StateFirstBoot, TriggerClusterJoinStart, model.StateJoining},
+		{model.StateJoining, TriggerJoinComplete, model.StateReady},
+	}
+	for _, tc := range cases {
+		got, err := Next(tc.from, tc.trigger)
+		if err != nil {
+			t.Errorf("Next(%q, %q) error: %v", tc.from, tc.trigger, err)
+			continue
+		}
+		if got != tc.want {
+			t.Errorf("Next(%q, %q) = %q, want %q", tc.from, tc.trigger, got, tc.want)
+		}
+	}
+}
+
+func TestFailedFromAllActive(t *testing.T) {
+	for _, state := range allActiveStates {
+		got, err := Next(state, TriggerFailed)
+		if err != nil {
+			t.Errorf("Next(%q, Failed) error: %v", state, err)
+			continue
+		}
+		if got != model.StateFailed {
+			t.Errorf("Next(%q, Failed) = %q, want %q", state, got, model.StateFailed)
+		}
+	}
+}
+
+func TestInvalidTransitions(t *testing.T) {
+	cases := []struct {
+		from    model.HostState
+		trigger Trigger
+	}{
+		{model.StateRegistered, TriggerPXEScriptServed},
+		{model.StateReady, TriggerPhoneHome},
+		{model.StatePXEReady, TriggerInstallWebhook},
+		{model.StateInstalling, TriggerRebuildRequested},
+		{model.StateRegistered, TriggerFailed},
+	}
+	for _, tc := range cases {
+		_, err := Next(tc.from, tc.trigger)
+		if err == nil {
+			t.Errorf("Next(%q, %q) expected error, got nil", tc.from, tc.trigger)
+		}
+	}
+}