🔒️(backend) prevent accessing files if they are not ready

With the addition of the ANALYSING state
files could be accessed in the short time they
were in that state.
We now require files to be in ready.

Also adds missing frontend types (no impact).

src/frontend/src/features/files/api/types.ts

@@ -5,7 +5,7 @@ export type ApiFileCreator = {
 }
 
 export type ApiFileType = 'background_image'
-export type ApiFileUploadState = 'pending' | 'ready'
+export type ApiFileUploadState = 'pending' | 'analyzing' | 'ready'
 
 export type ApiFileItem = {
   id: string // UUID