revert(upload): drop 1GB limit from outline PR, keep scope clean

The 50MB->1GB upload limit change is unrelated to this outline Q&A PR and
broke upstream CI (upload-controller.test.ts expects 413 at 50MB threshold).
Spinning it off into its own PR with matching test updates.

Author: WenhuaXia

packages/server/src/controllers/upload.ts

@@ -6,7 +6,7 @@ import { getProfileUploadDir } from '../services/hermes/upload-paths'
 import { MultipartParseError, parseMultipartBoundary, parseMultipartFilename, splitMultipart } from '../lib/multipart'
 import { drainRejectedRequest, nonDestroyingRequestBody } from '../lib/request-body'
 
-const MAX_UPLOAD_SIZE = 1024 * 1024 * 1024 // 50MB
+const MAX_UPLOAD_SIZE = 50 * 1024 * 1024 // 50MB
 
 function requestedProfile(ctx: any): string {
   return ctx.state?.profile?.name || getActiveProfileName() || 'default'