🔒️(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/backend/core/models.py

@@ -925,9 +925,9 @@ class File(BaseModel):
         return super().delete(using, keep_parents)
 
     @property
-    def is_pending_upload(self):
-        """Return whether the file is in a pending upload state"""
-        return self.upload_state == FileUploadStateChoices.PENDING
+    def is_ready(self):
+        """Return whether the file is in a ready upload state"""
+        return self.upload_state == FileUploadStateChoices.READY
 
     @property
     def extension(self):