fix(observability): repair Grafana Authentik OAuth2 relying-party login

The Authentik SSO button returned "Server Error" (500): the grafana provider had
a NULL authorization_flow and the authorize view crashed building a None flow
planner. After that, the login failed with "InternalError" — no email claim
reached Grafana, so it fell back to GET <api_url>/emails, which authentik 404s.

Unit env: request authentik real scopes (openid email profile, not the GitLab
user:email that crashes the authorize view); standard userinfo API_URL with no
?api=1 (Grafana v13 turns ?api=1 into a /emails 403); email/sub/preferred_username
attribute paths; ALLOW_SIGN_UP=true since the Anubis->Authentik guard fronts the
callback. scripts/authentik-grafana-sso-fix.sh idempotently re-applies the two
IdP-side causes (NULL authorization_flow; grafana-email-scope returning a bare
string instead of {"email":..}). Verified end to end: RP login lands on / and
/api/user answers 200 with the real email, user provisioned as Viewer.

scripts/authentik-grafana-sso-fix.sh

@@ -29,8 +29,8 @@
 # facts and the symptom returns verbatim. Re-run this after any such rebuild.
 # Every step is idempotent.
 #
-# Grafana's own half — SCOPES="openid email profile", USE_ID_TOKEN=true, no
-# `?api=1` on the API URL, ALLOW_SIGN_UP=true — lives in
+# Grafana's own half — SCOPES="openid email profile", a standard userinfo API_URL
+# with no `?api=1`, and ALLOW_SIGN_UP=true — lives in
 # dankclaw/observability/quadlet/grafana.container and deploys normally.
 #
 # Usage: authentik-grafana-sso-fix.sh          (override host: AUTHENTIK_HOST=…)