add possibility to disable delete and upload of books

backend/src/main/java/com/aiteacher/book/BookController.java

@@ -3,6 +3,7 @@ package com.aiteacher.book;
 import com.aiteacher.document.FigureEntity;
 import com.aiteacher.document.FigureRepository;
 import com.aiteacher.document.MarkdownStorageService;
+import org.springframework.beans.factory.annotation.Value;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.MediaType;
 import org.springframework.http.ResponseEntity;
@@ -22,6 +23,12 @@ public class BookController {
     private final FigureRepository figureRepository;
     private final MarkdownStorageService markdownStorageService;
 
+    @Value("${app.features.upload-enabled:true}")
+    private boolean uploadEnabled;
+
+    @Value("${app.features.delete-enabled:true}")
+    private boolean deleteEnabled;
+
     public BookController(BookService bookService, FigureRepository figureRepository,
                           MarkdownStorageService markdownStorageService) {
         this.bookService = bookService;
@@ -31,6 +38,7 @@ public class BookController {
 
     @PostMapping(consumes = "multipart/form-data")
     public ResponseEntity<?> upload(@RequestParam("file") MultipartFile file) throws IOException {
+        if (!uploadEnabled) return ResponseEntity.status(HttpStatus.METHOD_NOT_ALLOWED).build();
         Book book = bookService.upload(file);
         return ResponseEntity.status(HttpStatus.ACCEPTED).body(toSummaryResponse(book));
     }
@@ -51,6 +59,7 @@ public class BookController {
 
     @DeleteMapping("/{id}")
     public ResponseEntity<Void> delete(@PathVariable UUID id) {
+        if (!deleteEnabled) return ResponseEntity.status(HttpStatus.METHOD_NOT_ALLOWED).build();
         bookService.delete(id);
         return ResponseEntity.noContent().build();
     }