feat: add PDF/EPUB import functionality

- Add ImportTask/ImportResult types to domain.go
- Add TypeImportBook to asynqqueue for task routing
- Add CreateImportTask to producer and storage layers
- Add ClaimNextImportTask/FinishImportTask to Consumer interfaces
- Add import task handling to runner (polling + Asynq handler)
- Add BookImporter interface to bookstore for PDF/EPUB parsing
- Add backend API endpoints: POST/GET /api/admin/import
- Add SvelteKit UI at /admin/import with task list
- Add nav link in admin layout

Note: PDF/EPUB parsing is a placeholder - needs external library integration.

backend/internal/backend/handlers_import.go

@@ -0,0 +1,141 @@
+package backend
+
+import (
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"github.com/libnovel/backend/internal/storage"
+)
+
+type importRequest struct {
+	Title     string `json:"title"`
+	FileName  string `json:"file_name"`
+	FileType  string `json:"file_type"` // "pdf" or "epub"
+	ObjectKey string `json:"object_key"` // MinIO path to uploaded file
+}
+
+type importResponse struct {
+	TaskID string `json:"task_id"`
+	Slug   string `json:"slug"`
+}
+
+func (s *Server) handleAdminImport(w http.ResponseWriter, r *http.Request) {
+	if s.deps.Producer == nil {
+		jsonError(w, http.StatusServiceUnavailable, "task queue not configured")
+		return
+	}
+
+	ct := r.Header.Get("Content-Type")
+	var req importRequest
+	var objectKey string
+
+	if strings.HasPrefix(ct, "multipart/form-data") {
+		if err := r.ParseMultipartForm(32 << 20); err != nil {
+			jsonError(w, http.StatusBadRequest, "parse multipart: "+err.Error())
+			return
+		}
+		req.Title = r.FormValue("title")
+		req.FileName = r.FormValue("file_name")
+		req.FileType = r.FormValue("file_type")
+
+		file, header, err := r.FormFile("file")
+		if err != nil {
+			jsonError(w, http.StatusBadRequest, "parse file: "+err.Error())
+			return
+		}
+		defer file.Close()
+
+		if req.FileName == "" {
+			req.FileName = header.Filename
+		}
+		if req.FileType == "" {
+			req.FileType = strings.TrimPrefix(filepath.Ext(header.Filename), ".")
+		}
+
+		data, err := io.ReadAll(file)
+		if err != nil {
+			jsonError(w, http.StatusBadRequest, "read file: "+err.Error())
+			return
+		}
+
+		// Upload to MinIO directly via the store
+		objectKey = fmt.Sprintf("imports/%d_%s", time.Now().Unix(), header.Filename)
+		store, ok := s.deps.Producer.(*storage.Store)
+		if !ok {
+			jsonError(w, http.StatusInternalServerError, "storage not available")
+			return
+		}
+		if err := store.PutImportFile(r.Context(), objectKey, data); err != nil {
+			jsonError(w, http.StatusInternalServerError, "upload file: "+err.Error())
+			return
+		}
+	} else {
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			jsonError(w, http.StatusBadRequest, "parse body: "+err.Error())
+			return
+		}
+		objectKey = req.ObjectKey
+	}
+
+	if req.Title == "" {
+		jsonError(w, http.StatusBadRequest, "title is required")
+		return
+	}
+	if req.FileType != "pdf" && req.FileType != "epub" {
+		jsonError(w, http.StatusBadRequest, "file_type must be 'pdf' or 'epub'")
+		return
+	}
+
+	slug := strings.ToLower(strings.ReplaceAll(req.Title, " ", "-"))
+	slug = strings.Map(func(r rune) rune {
+		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') || r == '-' {
+			return r
+		}
+		return -1
+	}, slug)
+
+	taskID, err := s.deps.Producer.CreateImportTask(r.Context(), slug, req.Title, req.FileType, objectKey)
+	if err != nil {
+		jsonError(w, http.StatusInternalServerError, "create import task: "+err.Error())
+		return
+	}
+
+	writeJSON(w, 0, importResponse{
+		TaskID: taskID,
+		Slug:   slug,
+	})
+}
+
+func (s *Server) handleAdminImportStatus(w http.ResponseWriter, r *http.Request) {
+	taskID := r.PathValue("id")
+	if taskID == "" {
+		jsonError(w, http.StatusBadRequest, "task id required")
+		return
+	}
+
+	task, ok, err := s.deps.TaskReader.GetImportTask(r.Context(), taskID)
+	if err != nil {
+		jsonError(w, http.StatusInternalServerError, "get task: "+err.Error())
+		return
+	}
+	if !ok {
+		jsonError(w, http.StatusNotFound, "task not found")
+		return
+	}
+
+	writeJSON(w, 0, task)
+}
+
+func (s *Server) handleAdminImportList(w http.ResponseWriter, r *http.Request) {
+	tasks, err := s.deps.TaskReader.ListImportTasks(r.Context())
+	if err != nil {
+		jsonError(w, http.StatusInternalServerError, "list tasks: "+err.Error())
+		return
+	}
+	writeJSON(w, 0, map[string]any{"tasks": tasks})
+}

backend/internal/backend/server.go

@@ -244,6 +244,11 @@ func (s *Server) ListenAndServe(ctx context.Context) error {
 	// Admin data repair endpoints
 	mux.HandleFunc("POST /api/admin/dedup-chapters/{slug}", s.handleDedupChapters)
 
+	// Import (PDF/EPUB)
+	mux.HandleFunc("POST /api/admin/import", s.handleAdminImport)
+	mux.HandleFunc("GET /api/admin/import", s.handleAdminImportList)
+	mux.HandleFunc("GET /api/admin/import/{id}", s.handleAdminImportStatus)
+
 	// Voices list
 	mux.HandleFunc("GET /api/voices", s.handleVoices)