Expand skin upload schema and simplify texture storage

Updated the skin upload schema to accept both JSON and multipart/form-data content types, and to allow requests without a URL. Simplified the texture storage path in userService.js by removing subdirectory partitioning based on hash.

schemas/minecraftservices/minecraft/profile/skins.js

@@ -4,20 +4,29 @@ module.exports = {
     POST: {
         headers: z.object({
             "content-type": z.string()
-                .regex(/application\/json/i, { message: "Content-Type must be application/json" }),
+                .regex(/application\/json|multipart\/form-data/i, { 
+                    message: "Content-Type must be application/json or multipart/form-data" 
+                }),
             "authorization": z.string().min(1, { message: "Authorization header is required." })
         }),
-        body: z.object({
-            variant: z.enum(["classic", "slim"], { 
-                errorMap: () => ({ message: "Variant must be 'classic' or 'slim'." }) 
+        body: z.union([
+            z.object({
+                variant: z.enum(["classic", "slim"], { 
+                    errorMap: () => ({ message: "Variant must be 'classic' or 'slim'." }) 
+                }),
+                url: z.string()
+                    .url({ message: "Invalid URL format." })
+                    .max(2048, { message: "URL is too long." })
             }),
-            url: z.string()
-                .url({ message: "Invalid URL format." })
-                .max(2048, { message: "URL is too long." })
-        }),
+            z.object({
+                variant: z.enum(["classic", "slim"], { 
+                    errorMap: () => ({ message: "Variant must be 'classic' or 'slim'." }) 
+                }),
+            })
+        ]),
         error: {
             code: 400,
-            message: "Invalid skin URL or variant.",
+            message: "Invalid skin data, URL or variant.",
             error: "IllegalArgumentException"
         }
     }