fix: allow WRITE_ALL users to create and delete annotations

@RequirePermission on POST and DELETE annotation endpoints previously
only listed ANNOTATE_ALL. Users with WRITE_ALL (but not ANNOTATE_ALL)
received 403. A user who can write documents should also be able to
annotate them — both permissions now accepted on both methods.

Also updates canAnnotate in +layout.server.ts to match, so the UI
correctly reflects annotation capability for WRITE_ALL users.

Tests: AnnotationControllerTest (+2 RED→GREEN).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/src/main/java/org/raddatz/familienarchiv/controller/AnnotationController.java

@@ -35,7 +35,7 @@ public class AnnotationController {
 
     @PostMapping
     @ResponseStatus(HttpStatus.CREATED)
-    @RequirePermission(Permission.ANNOTATE_ALL)
+    @RequirePermission({Permission.ANNOTATE_ALL, Permission.WRITE_ALL})
     public DocumentAnnotation createAnnotation(
             @PathVariable UUID documentId,
             @RequestBody CreateAnnotationDTO dto,
@@ -47,7 +47,7 @@ public class AnnotationController {
 
     @DeleteMapping("/{annotationId}")
     @ResponseStatus(HttpStatus.NO_CONTENT)
-    @RequirePermission(Permission.ANNOTATE_ALL)
+    @RequirePermission({Permission.ANNOTATE_ALL, Permission.WRITE_ALL})
     public void deleteAnnotation(
             @PathVariable UUID documentId,
             @PathVariable UUID annotationId,