Extend authentik + FreshRSS session lifetimes

Authentik's default-authentication-login stage ships with
session_duration: seconds=0, so the SSO session died with the browser.
New blueprint raises it to 30 days for every app on that flow.

FreshRSS runs OIDC through Apache mod_auth_openidc, whose defaults are a
5 minute inactivity timeout and a ~7.5 hour max duration in a non-persistent
cookie. Bumped to a 30 day sliding inactivity window (refreshed on every
request) with a 90 day hard cap, and made the cookie persistent so it
survives a browser restart.

authentik/README.md

@@ -11,6 +11,22 @@ Authentik is deployed as the central identity provider, providing OIDC and LDAP
   - `blueprint-ldap.yaml` — LDAP provider (base DN: `DC=ldap,DC=goauthentik,DC=io`)
   - `blueprint-mail-oidc.yaml` — OAuth2/OIDC provider for Stalwart mail
   - `blueprint-vault-oidc.yaml` — OIDC provider for Vault
+  - `blueprint-argocd-oidc.yaml` — OIDC provider for ArgoCD
+  - `blueprint-freshrss-oidc.yaml` — OIDC provider for FreshRSS
+  - `blueprint-actualbudget-proxy.yaml` — Proxy provider for Actual Budget
+  - `blueprint-session-duration.yaml` — Session lifetime of the default authentication flow
+
+## Session lifetime
+
+Authentik ships the login stage of `default-authentication-flow` with
+`session_duration: seconds=0`, i.e. the SSO session dies when the browser closes.
+`blueprint-session-duration.yaml` raises this to 30 days for every app that uses
+that flow (FreshRSS, ArgoCD, Vault, Actual Budget, mail).
+
+The expiry is **absolute** — Authentik does not extend a session on activity. A
+sliding window has to come from the application itself; FreshRSS does this via
+`OIDC_SESSION_INACTIVITY_TIMEOUT` (see `freshrss/freshrss-deployment.yaml`), which
+Apache mod_auth_openidc refreshes on every request.
 
 ## LDAP Outpost
 

authentik/blueprint-session-duration.yaml

@@ -0,0 +1,27 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: authentik-blueprint-session
+data:
+  session-duration.yaml: |
+    version: 1
+    metadata:
+      name: Session duration
+    entries:
+      # Overrides the login stage of the built-in `default-authentication-flow`,
+      # which every OIDC/proxy provider in this cluster authenticates against.
+      # authentik ships this stage with `session_duration: seconds=0`, which means
+      # "until the browser is closed" — that is why re-logins were so frequent.
+      #
+      # Note: authentik's session expiry is absolute (counted from login), it does
+      # not slide on activity. The sliding window lives in the applications, e.g.
+      # OIDC_SESSION_INACTIVITY_TIMEOUT in freshrss/freshrss-deployment.yaml.
+      - model: authentik_stages_user_login.userloginstage
+        state: present
+        identifiers:
+          name: default-authentication-login
+        attrs:
+          session_duration: days=30
+          # Uncomment to show a "Remember me on this device" checkbox that adds
+          # this offset on top of session_duration when ticked (0 = hidden).
+          # remember_me_offset: days=60