fix: substitution of content when sending an image to a profile (#3869)

* fix: Limit public uploads to basic image types

* test

shared/validations.ts

@@ -1,3 +1,24 @@
+export const AttachmentValidation = {
+  /** The limited allowable mime-types for user and team avatars */
+  avatarContentTypes: ["image/jpg", "image/jpeg", "image/png"],
+
+  /** Image mime-types commonly supported by modern browsers */
+  imageContentTypes: [
+    "image/jpg",
+    "image/jpeg",
+    "image/pjpeg",
+    "image/png",
+    "image/apng",
+    "image/avif",
+    "image/gif",
+    "image/webp",
+    "image/svg",
+    "image/svg+xml",
+    "image/bmp",
+    "image/tiff",
+  ],
+};
+
 export const CollectionValidation = {
   /** The maximum length of the collection description */
   maxDescriptionLength: 1000,