feat: implement Havenllo single-board kanban (Go+SQLite backend, Preact/Vite frontend)

- Single fixed 'Haven' board: lists (To do/In progress/Done) + cards, no multi-board
- Go 1.24 backend, CGO-free modernc.org/sqlite, embedded SPA, REST /api
- Preact + Vite + TS frontend, native HTML5 drag-and-drop, optimistic UI, dark Haven theme
- PVC (nfs-client) for SQLite, root container on NFS, simple nginx ingress havenllo.haven
- Dockerfile multi-arch build, Gitea CI via pipeline-actions@main

internal/app/service_test.go

@@ -0,0 +1,97 @@
+package app_test
+
+import (
+	"context"
+	"errors"
+	"path/filepath"
+	"testing"
+
+	"havenllo/internal/app"
+	"havenllo/internal/database"
+	"havenllo/internal/domain"
+)
+
+func newService(t *testing.T) (*app.Service, func()) {
+	t.Helper()
+	db, err := database.Open(context.Background(), filepath.Join(t.TempDir(), "havenllo.db"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	return app.New(db), func() { _ = db.Close() }
+}
+
+func TestLastListProtection(t *testing.T) {
+	t.Parallel()
+	service, closeDB := newService(t)
+	defer closeDB()
+	ctx := context.Background()
+	lists, err := service.Lists(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for _, list := range lists[:2] {
+		if err := service.DeleteList(ctx, list.ID); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if err := service.DeleteList(ctx, lists[2].ID); !errors.Is(err, domain.ErrLastList) {
+		t.Fatalf("DeleteList error = %v, want ErrLastList", err)
+	}
+}
+
+func TestCardMoveNormalizesCrowdedPositions(t *testing.T) {
+	t.Parallel()
+	service, closeDB := newService(t)
+	defer closeDB()
+	ctx := context.Background()
+	lists, err := service.Lists(ctx)
+	if err != nil {
+		t.Fatal(err)
+	}
+	first := lists[0]
+	a, err := service.CreateCard(ctx, first.ID, "a", "", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	b, err := service.CreateCard(ctx, first.ID, "b", "", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	position := a.Position + 0.00001
+	if _, err := service.UpdateCard(ctx, b.ID, app.CardPatch{Position: &position}); err != nil {
+		t.Fatal(err)
+	}
+	cards, err := service.Cards(ctx, first.ID)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(cards) != 2 || cards[1].Position-cards[0].Position < 0.0001 {
+		t.Fatalf("cards were not normalized: %#v", cards)
+	}
+}
+
+func TestCardMoveAndCascade(t *testing.T) {
+	t.Parallel()
+	service, closeDB := newService(t)
+	defer closeDB()
+	ctx := context.Background()
+	lists, _ := service.Lists(ctx)
+	card, err := service.CreateCard(ctx, lists[0].ID, "move me", "", nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	target := lists[1].ID
+	moved, err := service.UpdateCard(ctx, card.ID, app.CardPatch{ListID: &target})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if moved.ListID != target {
+		t.Fatalf("card list = %d, want %d", moved.ListID, target)
+	}
+	if err := service.DeleteList(ctx, target); err != nil {
+		t.Fatal(err)
+	}
+	if _, err := service.Card(ctx, card.ID); !errors.Is(err, domain.ErrNotFound) {
+		t.Fatalf("card after list deletion = %v, want not found", err)
+	}
+}