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
- 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/cmd/pdf-to-chapters/main.go

@@ -1,165 +0,0 @@
-package main
-
-import (
-	"fmt"
-	"log"
-	"os"
-	"regexp"
-	"strings"
-
-	"github.com/ledongthuc/pdf"
-)
-
-func main() {
-	if len(os.Args) < 2 {
-		fmt.Println("Usage: pdf-to-chapters <input.pdf>")
-		os.Exit(1)
-	}
-
-	inputPath := os.Args[1]
-
-	if err := processPDF(inputPath); err != nil {
-		log.Fatal(err)
-	}
-}
-
-func processPDF(inputPath string) error {
-	pdf.DebugOn = false
-
-	f, r, err := pdf.Open(inputPath)
-	if err != nil {
-		return fmt.Errorf("failed to open PDF: %w", err)
-	}
-	defer f.Close()
-
-	totalPages := r.NumPage()
-	fmt.Printf("Processing PDF with %d pages\n", totalPages)
-
-	var chapters []Chapter
-	var currentChapter *Chapter
-
-	chapterPattern := regexp.MustCompile(`The Eminence in Shadow\s+(\d+)\s*-\s*(\d+)`)
-
-	for i := 1; i <= totalPages; i++ {
-		page := r.Page(i)
-		if err := page.IsValid(); err != nil {
-			log.Printf("Warning: page %d not valid: %v", i, err)
-			continue
-		}
-
-		text, err := page.GetPlainText(nil)
-		if err != nil {
-			log.Printf("Warning: failed to extract text from page %d: %v", i, err)
-			continue
-		}
-
-		// Check for chapter header on this page
-		matches := chapterPattern.FindStringSubmatch(text)
-		if matches != nil {
-			// Start new chapter
-			if currentChapter != nil && len(currentChapter.Content) > 0 {
-				chapters = append(chapters, *currentChapter)
-			}
-
-			chapterNum := matches[1]
-			currentChapter = &Chapter{
-				Number:    chapterNum,
-				StartPage: i,
-				Content:   text,
-			}
-			continue
-		}
-
-		// Append to current chapter
-		if currentChapter != nil {
-			currentChapter.Content += "\n" + text
-		}
-	}
-
-	// Don't forget last chapter
-	if currentChapter != nil && len(currentChapter.Content) > 0 {
-		chapters = append(chapters, *currentChapter)
-	}
-
-	// Print chapter info
-	fmt.Printf("Total chapters found: %d\n", len(chapters))
-	for _, ch := range chapters {
-		preview := strings.TrimSpace(ch.Content)
-		if len(preview) > 200 {
-			preview = preview[:200] + "..."
-		}
-		fmt.Printf("Chapter %s (page %d): %s\n", ch.Number, ch.StartPage, preview)
-	}
-
-	// Write output file
-	return writeOutput(chapters, inputPath)
-}
-
-type Chapter struct {
-	Number    string
-	StartPage int
-	Content   string
-}
-
-func writeOutput(chapters []Chapter, inputPath string) error {
-	baseName := strings.TrimSuffix(inputPath, ".pdf")
-	outPath := baseName + "_chapters.txt"
-
-	f, err := os.Create(outPath)
-	if err != nil {
-		return fmt.Errorf("failed to create output: %w", err)
-	}
-	defer f.Close()
-
-	for i, ch := range chapters {
-		if i > 0 {
-			fmt.Fprintln(f)
-		}
-		fmt.Fprintf(f, "## Chapter %s\n\n", ch.Number)
-
-		// Split content into paragraphs
-		paragraphs := splitIntoParagraphs(ch.Content)
-		for _, para := range paragraphs {
-			trimmed := strings.TrimSpace(para)
-			if len(trimmed) > 0 {
-				fmt.Fprintln(f, trimmed)
-				fmt.Fprintln(f)
-			}
-		}
-	}
-
-	fmt.Printf("\nOutput written to: %s\n", outPath)
-	return nil
-}
-
-func splitIntoParagraphs(text string) []string {
-	lines := strings.Split(text, "\n")
-	var paragraphs []string
-	var currentPara strings.Builder
-
-	for _, line := range lines {
-		trimmed := strings.TrimSpace(line)
-		// Skip empty lines and very short lines (likely headers/page numbers)
-		if len(trimmed) == 0 {
-			if currentPara.Len() > 0 {
-				paragraphs = append(paragraphs, currentPara.String())
-				currentPara.Reset()
-			}
-			continue
-		}
-		if len(trimmed) < 3 {
-			continue
-		}
-
-		if currentPara.Len() > 0 {
-			currentPara.WriteString(" ")
-		}
-		currentPara.WriteString(trimmed)
-	}
-
-	if currentPara.Len() > 0 {
-		paragraphs = append(paragraphs, currentPara.String())
-	}
-
-	return paragraphs
-}