fix(uploads): restore SUPPORTED_IMAGE_EXTENSIONS import in upload route

Build broke because biome auto-fix collapsed my multi-import edit and
dropped SUPPORTED_IMAGE_EXTENSIONS, which is still referenced for the
generic-MIME image fallback at line 298.

Author: waleedlatif1

apps/sim/app/api/files/upload/route.ts

@@ -14,7 +14,11 @@ import { captureServerEvent } from '@/lib/posthog/server'
 import type { StorageContext } from '@/lib/uploads/config'
 import { generateWorkspaceFileKey } from '@/lib/uploads/contexts/workspace/workspace-file-manager'
 import { isImageFileType, resolveFileType } from '@/lib/uploads/utils/file-utils'
-import { SUPPORTED_ATTACHMENT_EXTENSIONS, validateFileType } from '@/lib/uploads/utils/validation'
+import {
+  SUPPORTED_ATTACHMENT_EXTENSIONS,
+  SUPPORTED_IMAGE_EXTENSIONS,
+  validateFileType,
+} from '@/lib/uploads/utils/validation'
 import { getUserEntityPermissions } from '@/lib/workspaces/permissions/utils'
 import {
   createErrorResponse,