feat: add v2 stack (backend, runner, ui-v2) with release workflow

- backend/: Go API server and runner binaries with PocketBase + MinIO storage
- ui-v2/: SvelteKit frontend rewrite
- docker-compose-new.yml: compose file for the v2 stack
- .gitea/workflows/release-v2.yaml: CI/CD for backend, runner, and ui-v2 Docker Hub images
- scripts/pb-init.sh: migrate from wget to curl, add superuser bootstrap for fresh installs
- .env.example: document DOCKER_BUILDKIT=1 for Colima users

backend/cmd/backend/main.go

@@ -0,0 +1,125 @@
+// Command backend is the LibNovel HTTP API server.
+//
+// It exposes all endpoints consumed by the SvelteKit UI: book/chapter reads,
+// scrape-task creation, presigned MinIO URLs, audio-task creation, reading
+// progress, live novelfire.net browse/search, and Kokoro voice list.
+//
+// All heavy lifting (scraping, TTS generation) is delegated to the runner
+// binary via PocketBase task records. The backend never scrapes directly.
+//
+// Usage:
+//
+//	backend          # start HTTP server (blocks until SIGINT/SIGTERM)
+package main
+
+import (
+	"context"
+	"fmt"
+	"log/slog"
+	"os"
+	"os/signal"
+	"syscall"
+
+	"github.com/libnovel/backend/internal/backend"
+	"github.com/libnovel/backend/internal/config"
+	"github.com/libnovel/backend/internal/kokoro"
+	"github.com/libnovel/backend/internal/storage"
+)
+
+// version and commit are set at build time via -ldflags.
+var (
+	version = "dev"
+	commit  = "unknown"
+)
+
+func main() {
+	if err := run(); err != nil {
+		fmt.Fprintf(os.Stderr, "backend: fatal: %v\n", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	cfg := config.Load()
+
+	// ── Logger ───────────────────────────────────────────────────────────────
+	log := buildLogger(cfg.LogLevel)
+	log.Info("backend starting",
+		"version", version,
+		"commit", commit,
+		"addr", cfg.HTTP.Addr,
+	)
+
+	// ── Context: cancel on SIGINT / SIGTERM ──────────────────────────────────
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+
+	// ── Storage ──────────────────────────────────────────────────────────────
+	store, err := storage.NewStore(ctx, cfg, log)
+	if err != nil {
+		return fmt.Errorf("init storage: %w", err)
+	}
+
+	// ── Kokoro (voice list only; audio generation is done by the runner) ─────
+	var kokoroClient kokoro.Client
+	if cfg.Kokoro.URL != "" {
+		kokoroClient = kokoro.New(cfg.Kokoro.URL)
+		log.Info("kokoro voices enabled", "url", cfg.Kokoro.URL)
+	} else {
+		log.Info("KOKORO_URL not set — voice list will use built-in fallback")
+		kokoroClient = &noopKokoro{}
+	}
+
+	// ── Backend server ───────────────────────────────────────────────────────
+	srv := backend.New(
+		backend.Config{
+			Addr:         cfg.HTTP.Addr,
+			DefaultVoice: cfg.Kokoro.DefaultVoice,
+			Version:      version,
+			Commit:       commit,
+		},
+		backend.Dependencies{
+			BookReader:    store,
+			RankingStore:  store,
+			AudioStore:    store,
+			PresignStore:  store,
+			ProgressStore: store,
+			Producer:      store,
+			TaskReader:    store,
+			Kokoro:        kokoroClient,
+			Log:           log,
+		},
+	)
+
+	return srv.ListenAndServe(ctx)
+}
+
+// ── Helpers ───────────────────────────────────────────────────────────────────
+
+func buildLogger(level string) *slog.Logger {
+	var lvl slog.Level
+	switch level {
+	case "debug":
+		lvl = slog.LevelDebug
+	case "warn":
+		lvl = slog.LevelWarn
+	case "error":
+		lvl = slog.LevelError
+	default:
+		lvl = slog.LevelInfo
+	}
+	return slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: lvl}))
+}
+
+// noopKokoro is a no-op implementation used when KOKORO_URL is not set.
+// The backend only uses Kokoro for the voice list; audio generation is the
+// runner's responsibility. With no URL the built-in fallback list is served.
+type noopKokoro struct{}
+
+func (n *noopKokoro) GenerateAudio(_ context.Context, _, _ string) ([]byte, error) {
+	return nil, fmt.Errorf("kokoro not configured (KOKORO_URL is empty)")
+}
+
+func (n *noopKokoro) ListVoices(_ context.Context) ([]string, error) {
+	return nil, nil
+}

backend/cmd/backend/main_test.go

@@ -0,0 +1,57 @@
+package main
+
+import (
+	"os"
+	"testing"
+)
+
+// TestBuildLogger verifies that buildLogger returns a non-nil logger for each
+// supported log level string and for unknown values.
+func TestBuildLogger(t *testing.T) {
+	for _, level := range []string{"debug", "info", "warn", "error", "unknown", ""} {
+		l := buildLogger(level)
+		if l == nil {
+			t.Errorf("buildLogger(%q) returned nil", level)
+		}
+	}
+}
+
+// TestNoopKokoro verifies that the no-op Kokoro stub returns the expected
+// sentinel error from GenerateAudio and nil, nil from ListVoices.
+func TestNoopKokoro(t *testing.T) {
+	noop := &noopKokoro{}
+
+	_, err := noop.GenerateAudio(t.Context(), "text", "af_bella")
+	if err == nil {
+		t.Fatal("noopKokoro.GenerateAudio: expected error, got nil")
+	}
+
+	voices, err := noop.ListVoices(t.Context())
+	if err != nil {
+		t.Fatalf("noopKokoro.ListVoices: unexpected error: %v", err)
+	}
+	if voices != nil {
+		t.Fatalf("noopKokoro.ListVoices: expected nil slice, got %v", voices)
+	}
+}
+
+// TestRunStorageUnreachable verifies that run() fails fast and returns a
+// descriptive error when PocketBase is unreachable.
+func TestRunStorageUnreachable(t *testing.T) {
+	// Point at an address nothing is listening on.
+	t.Setenv("POCKETBASE_URL", "http://127.0.0.1:19999")
+	// Use a fast listen address so we don't accidentally start a real server.
+	t.Setenv("BACKEND_HTTP_ADDR", "127.0.0.1:0")
+
+	err := run()
+	if err == nil {
+		t.Fatal("run() should have returned an error when storage is unreachable")
+	}
+
+	t.Logf("got expected error: %v", err)
+}
+
+// TestMain runs the test suite. No special setup required.
+func TestMain(m *testing.M) {
+	os.Exit(m.Run())
+}