fix: Clear erroneous validation_policies on matrix-invitation-prompt

The prompt stage had 16 unrelated system policies bound (OOBE, user
settings, recovery, etc.), likely from a "select all" slip while
configuring it manually. They crash when evaluated in an anonymous
enrollment context (AnonymousUser has no group_attributes, etc.),
surfacing as opaque errors after form submit. Cleared live and via
the blueprint so re-application doesn't reintroduce them.

apps/authentik/authentik-blueprints.yaml

@@ -23,6 +23,18 @@ data:
           title: matrix-invitation
           designation: enrollment
 
+      # The prompt stage had accumulated 16 unrelated system validation_policies
+      # (e.g. default-user-settings-authorization, default-oobe-password-usable)
+      # from manual UI setup, likely a "select all" slip in the policy picker.
+      # These crash on an anonymous enrollment context ('AnonymousUser' object
+      # has no attribute 'group_attributes', etc). A prompt stage needs none here.
+      - model: authentik_stages_prompt.promptstage
+        state: present
+        identifiers:
+          name: matrix-invitation-prompt
+        attrs:
+          validation_policies: []
+
       # Correct stage chain, mirroring the working matrix-enrollment flow:
       # Invite -> Prompt (username/email/password) -> Write -> Password -> Login
       # Root cause of the original bug: only Invite+Prompt were bound, both at