Clean up implementation plan: remove duplicate Step 3.2

- Remove duplicate extractPDFCover function documentation
- Fixes issue identified during plan review where Step 3.2
  appeared twice with identical content

IMPLEMENTATION_PLAN_COVER_PDF.md

@@ -449,84 +449,6 @@ func (s *MediaScanner) extractPDFMetadata(path string) (*MediaMetadata, error) {
 
 **Exact Code to INSERT:**
 
-```go
-// extractPDFCover extracts a cover image from a PDF file.
-// It uses pdfcpu to extract images from the first page.
-// Returns the path to the saved cover, or empty string if no cover found.
-func (s *MediaScanner) extractPDFCover(pdfPath string) (string, error) {
-	// Create a temporary directory for extracted images
-	tmpDir, err := os.MkdirTemp("", "pdf-cover-")
-	if err != nil {
-		return "", fmt.Errorf("failed to create temp dir: %v", err)
-	}
-	defer os.RemoveAll(tmpDir)
-
-	// Use pdfcpu API to extract images from first page
-	// ExtractImagesFile(inFile, outDir string, selectedPages []string, conf *model.Configuration) error
-	err = pdfcpuapi.ExtractImagesFile(pdfPath, tmpDir, []string{"1"}, nil)
-	if err != nil {
-		// No images found or extraction failed - this is OK, just return empty
-		return "", nil
-	}
-
-	// Check for extracted images in the temp directory
-	entries, err := os.ReadDir(tmpDir)
-	if err != nil || len(entries) == 0 {
-		return "", nil
-	}
-
-	// Find the largest image (likely the cover)
-	var largestImage string
-	var largestSize int64
-
-	for _, entry := range entries {
-		if entry.IsDir() {
-			continue
-		}
-		info, err := entry.Info()
-		if err != nil {
-			continue
-		}
-		// Skip very small files (likely thumbnails or icons)
-		if info.Size() < 1000 {
-			continue
-		}
-		if info.Size() > largestSize {
-			largestImage = filepath.Join(tmpDir, entry.Name())
-			largestSize = info.Size()
-		}
-	}
-
-	if largestImage == "" {
-		return "", nil
-	}
-
-	// Read the image
-	imageData, err := os.ReadFile(largestImage)
-	if err != nil || len(imageData) == 0 {
-		return "", nil
-	}
-
-	// Save cover to disk (same pattern as comics: {pdf_path}.cover.jpg)
-	coverPath := pdfPath + ".cover.jpg"
-	if err := os.WriteFile(coverPath, imageData, 0644); err != nil {
-		return "", fmt.Errorf("failed to write cover file: %v", err)
-	}
-
-	return coverPath, nil
-}
-```
-
----
-
-### Step 3.2: Add extractPDFCover Helper Function
-
-**File:** `internal/services/media_scanner.go`
-
-**Location:** AFTER the extractPDFMetadata function, BEFORE the ComicInfo struct
-
-**Exact Code to INSERT:**
-
 ```go
 // extractPDFCover extracts a cover image from a PDF file.
 // It uses pdfcpu API to extract images from the first page.