feat: change volume from string to integer type

Parser:
- Change volume type from Option<String> to Option<i32>
- Parse volume as integer to remove leading zeros
- Keep original title with volume info

Indexer:
- Update SQL queries to insert volume as integer
- Add volume column to INSERT and UPDATE statements

API:
- Change BookItem.volume and BookDetails.volume to Option<i32>
- Add natural sorting for books

Backoffice:
- Update volume type to number
- Update book detail page
- Add CSS styles

apps/backoffice/app/books/[id]/page.tsx

@@ -68,6 +68,13 @@ export default async function BookDetailPage({
               <span className={`book-kind ${book.kind}`}>{book.kind.toUpperCase()}</span>
             </div>
             
+            {book.volume && (
+              <div className="meta-row">
+                <span className="meta-label">Volume:</span>
+                <span>{book.volume}</span>
+              </div>
+            )}
+            
             {book.language && (
               <div className="meta-row">
                 <span className="meta-label">Language:</span>
@@ -87,10 +94,50 @@ export default async function BookDetailPage({
               <span>{library?.name || book.library_id}</span>
             </div>
 
+            {book.series && (
+              <div className="meta-row">
+                <span className="meta-label">Series:</span>
+                <span>{book.series}</span>
+              </div>
+            )}
+
+            {book.file_format && (
+              <div className="meta-row">
+                <span className="meta-label">File Format:</span>
+                <span>{book.file_format.toUpperCase()}</span>
+              </div>
+            )}
+
+            {book.file_parse_status && (
+              <div className="meta-row">
+                <span className="meta-label">Parse Status:</span>
+                <span className={`status-${book.file_parse_status}`}>{book.file_parse_status}</span>
+              </div>
+            )}
+
+            {book.file_path && (
+              <div className="meta-row">
+                <span className="meta-label">File Path:</span>
+                <code className="file-path">{book.file_path}</code>
+              </div>
+            )}
+
             <div className="meta-row">
-              <span className="meta-label">ID:</span>
+              <span className="meta-label">Book ID:</span>
               <code className="book-id">{book.id}</code>
             </div>
+
+            <div className="meta-row">
+              <span className="meta-label">Library ID:</span>
+              <code className="book-id">{book.library_id}</code>
+            </div>
+
+            {book.updated_at && (
+              <div className="meta-row">
+                <span className="meta-label">Updated:</span>
+                <span>{new Date(book.updated_at).toLocaleString()}</span>
+              </div>
+            )}
           </div>
         </div>
       </div>

apps/backoffice/app/books/page.tsx

@@ -36,6 +36,9 @@ export default async function BooksPage({
         volume: hit.volume,
         language: hit.language,
         page_count: null,
+        file_path: null,
+        file_format: null,
+        file_parse_status: null,
         updated_at: ""
       }));
       totalHits = searchResponse.estimated_total_hits;