Initial commit: full Phases 1-6 implementation

Post-repair hardware validation pipeline for Proxmox cluster hosts.
Go orchestrator + in-image agent + mkosi live image + bundled dnsmasq
PXE + SQLite + HTMX/SSE UI + notify registry + janitor + full docs.

internal/orchestrator/statemachine_test.go

@@ -0,0 +1,67 @@
+package orchestrator_test
+
+import (
+	"testing"
+
+	"vetting/internal/model"
+	"vetting/internal/orchestrator"
+)
+
+func TestNextForOverride(t *testing.T) {
+	tests := []struct {
+		name        string
+		from        model.RunState
+		failedStage string
+		want        model.RunState
+		wantErr     bool
+	}{
+		{"storage override", model.StateFailedHolding, "Storage", model.StateStorage, false},
+		{"smart override", model.StateFailedHolding, "SMART", model.StateSMART, false},
+		{"inventory override", model.StateFailedHolding, "Inventory", model.StateInventoryCheck, false},
+		{"unknown stage", model.StateFailedHolding, "NotAStage", "", true},
+		{"not holding", model.StateStorage, "Storage", "", true},
+	}
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			got, err := orchestrator.NextForOverride(tc.from, tc.failedStage)
+			if tc.wantErr {
+				if err == nil {
+					t.Fatalf("expected error, got %q", got)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if got != tc.want {
+				t.Fatalf("got %q, want %q", got, tc.want)
+			}
+		})
+	}
+}
+
+func TestNextStageWalk(t *testing.T) {
+	// Walking StageCompleted from each stage should land on the next
+	// one in the canonical order, and from Reporting onto Completed.
+	chain := []model.RunState{
+		model.StateInventoryCheck,
+		model.StateSpecValidate,
+		model.StateSMART,
+		model.StateCPUStress,
+		model.StateStorage,
+		model.StateNetwork,
+		model.StateGPU,
+		model.StatePSU,
+		model.StateReporting,
+		model.StateCompleted,
+	}
+	for i := 0; i < len(chain)-1; i++ {
+		got, err := orchestrator.Next(chain[i], orchestrator.TriggerStageCompleted)
+		if err != nil {
+			t.Fatalf("Next(%q): %v", chain[i], err)
+		}
+		if got != chain[i+1] {
+			t.Fatalf("Next(%q) = %q, want %q", chain[i], got, chain[i+1])
+		}
+	}
+}