feat: add poimen-memory as an Authentik service-to-service client

Client credentials + device code grant, no browser redirect (empty
redirect_uris) - unlike every other SERVICES entry which is
authorization_code web SSO. First real step toward replacing
poimen-memory's static API key with a proper JWT flow.

k8s/infra/iam/scripts/authentik-provision.py

@@ -415,6 +415,15 @@ SERVICES = {
         "launch_url": "https://vault.riotpiao.com",
         "display_name": "Vault",
     },
+    "poimen-memory": {
+        # Service-to-service API auth (no browser redirect) - generate secret on first run.
+        "client_secret_source": ("poimen", "poimen-memory-oidc", "CLIENT_SECRET"),
+        "generate_if_missing": True,
+        "extra_secret_literals": {"client-id": "poimen-memory"},
+        "redirect_uris": [],  # No browser flow, service-to-service only
+        "launch_url": "https://memory.riotpiao.com",
+        "display_name": "Poimen Memory",
+    },
 }
 
 app_pks_for_binding = []
@@ -501,6 +510,16 @@ for name, cfg in SERVICES.items():
             "config.json": immich_config_json,
         })
 
+    # Service-to-service (client_credentials): poimen-memory
+    # Browser SSO (authorization_code): all others
+    grant_types = [
+        "urn:ietf:params:oauth:grant-type:device_code",  # device code flow (CLI/headless)
+        "client_credentials"  # service-to-service
+    ] if name == "poimen-memory" else [
+        "authorization_code",  # web SSO
+        "refresh_token"  # long-lived sessions
+    ]
+
     provider = get_or_create(
         "/api/v3/providers/oauth2/", "/api/v3/providers/oauth2/",
         f"name={name}",
@@ -520,7 +539,7 @@ for name, cfg in SERVICES.items():
             # every login with "Invalid grant_type for provider" ->
             # invalid_request. authorization_code = the web SSO flow all these
             # apps use; refresh_token = long-lived sessions (offline_access).
-            "grant_types": ["authorization_code", "refresh_token"],
+            "grant_types": grant_types,
             "redirect_uris": [
                 {"matching_mode": "strict", "url": u} for u in cfg["redirect_uris"]
             ],
@@ -530,7 +549,7 @@ for name, cfg in SERVICES.items():
         # truth in the k8s Secret, and re-sending it here is harmless anyway).
         patch_existing={
             "property_mappings": provider_mappings,
-            "grant_types": ["authorization_code", "refresh_token"],
+            "grant_types": grant_types,
             "redirect_uris": [
                 {"matching_mode": "strict", "url": u} for u in cfg["redirect_uris"]
             ],