fix(library): sync allowed extensions across service, schema, and tests

Add .epub and .pdf to comics type, add .pdf to manga type, and ensure
avif/tiff/tif extensions are consistently included in manga across all
layers. Update test fixtures to match the canonical extension lists.

cmd/server/tests/library_test_comprehensive_test.go

@@ -556,7 +556,7 @@ func TestLibraryTypes(t *testing.T) {
 					"id":                 uuid.New().String(),
 					"name":               "comics",
 					"description":        "Comic book archives and image formats",
-					"allowed_extensions": []string{".cbz", ".cbr", ".pdf"},
+					"allowed_extensions": []string{".cbz", ".cbr", ".cb7", ".cbt", ".epub", ".pdf"},
 				},
 			}
 			w.WriteHeader(http.StatusOK)