Add Authentik OIDC login for ArgoCD (#284)

## Summary
- Add Authentik OAuth2 provider + application blueprint for ArgoCD (ringtail side)
- Add OIDC config to ArgoCD ConfigMap with Authentik as identity provider (indri side)
- Map Authentik `admins` group to ArgoCD `role:admin` via RBAC policy
- ExternalSecrets on both sides pull `argocd-client-secret` from 1Password
- Local admin password remains as break-glass — both login methods coexist

## Pre-deployment manual step
Add `argocd-client-secret` field to "Authentik (blumeops)" in 1Password with a random value (e.g., `openssl rand -hex 32`).

## Deployment order
1. Sync Authentik app on ringtail first (blueprint + secret + worker env var)
2. Sync ArgoCD app on indri second (cm, rbac, ExternalSecret)

## Verification
- [ ] `argocd-client-secret` field added to 1Password
- [ ] Authentik app synced on ringtail — blueprint applied, provider created
- [ ] ArgoCD app synced on indri — OIDC config applied
- [ ] SSO login works: visit `https://argocd.ops.eblu.me` → "Log in via Authentik" → admin access
- [ ] Break-glass: local admin/password login still works

Reviewed-on: #284

argocd/manifests/authentik/configmap-blueprint.yaml

@@ -246,6 +246,64 @@ data:
           negate: false
           timeout: 30
 
+  argocd.yaml: |
+    version: 1
+    metadata:
+      name: BlumeOps ArgoCD SSO
+      labels:
+        blueprints.goauthentik.io/description: "ArgoCD OIDC provider and application"
+    entries:
+      # OAuth2 provider for ArgoCD
+      - model: authentik_providers_oauth2.oauth2provider
+        id: argocd-provider
+        identifiers:
+          name: ArgoCD
+        attrs:
+          name: ArgoCD
+          authorization_flow: !Find [authentik_flows.flow, [slug, default-provider-authorization-implicit-consent]]
+          invalidation_flow: !Find [authentik_flows.flow, [slug, default-provider-invalidation-flow]]
+          client_type: confidential
+          client_id: argocd
+          client_secret: !Env AUTHENTIK_ARGOCD_CLIENT_SECRET
+          redirect_uris:
+            - matching_mode: strict
+              url: https://argocd.ops.eblu.me/auth/callback
+            - matching_mode: strict
+              url: https://argocd.tail8d86e.ts.net/auth/callback
+          signing_key: !Find [authentik_crypto.certificatekeypair, [name, authentik Self-signed Certificate]]
+          property_mappings:
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, openid]]
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, email]]
+            - !Find [authentik_providers_oauth2.scopemapping, [scope_name, profile]]
+          sub_mode: hashed_user_id
+          include_claims_in_id_token: true
+
+      # ArgoCD application — linked to the OAuth2 provider
+      - model: authentik_core.application
+        id: argocd-app
+        identifiers:
+          slug: argocd
+        attrs:
+          name: ArgoCD
+          slug: argocd
+          provider: !KeyOf argocd-provider
+          meta_launch_url: https://argocd.ops.eblu.me
+          policy_engine_mode: any
+
+      # Policy binding — restrict ArgoCD to admins group
+      - model: authentik_policies.policybinding
+        identifiers:
+          order: 0
+          target: !KeyOf argocd-app
+          group: !Find [authentik_core.group, [name, admins]]
+        attrs:
+          target: !KeyOf argocd-app
+          group: !Find [authentik_core.group, [name, admins]]
+          order: 0
+          enabled: true
+          negate: false
+          timeout: 30
+
   jellyfin.yaml: |
     version: 1
     metadata:

argocd/manifests/authentik/deployment-worker.yaml

@@ -73,6 +73,11 @@ spec:
                 secretKeyRef:
                   name: authentik-config
                   key: jellyfin-client-secret
+            - name: AUTHENTIK_ARGOCD_CLIENT_SECRET
+              valueFrom:
+                secretKeyRef:
+                  name: authentik-config
+                  key: argocd-client-secret
           volumeMounts:
             - name: blueprints
               mountPath: /blueprints/custom

argocd/manifests/authentik/external-secret.yaml

@@ -53,3 +53,7 @@ spec:
       remoteRef:
         key: "Authentik (blumeops)"
         property: jellyfin-client-secret
+    - secretKey: argocd-client-secret
+      remoteRef:
+        key: "Authentik (blumeops)"
+        property: argocd-client-secret