headplane: point OIDC at the real Authentik app; rotate tailnet keys

The Authentik provider and application now exist (slug "headplane", which
is what makes the issuer .../application/o/headplane/), so the client ID
is a real value rather than a placeholder, and the client secret and
headscale API key are in sops.

The tailscale pre-auth keys for neptun and jupiter are rotated because
the tailnet was recreated from scratch: the old headscale database went
with the VPS's OS disk, so every key issued against it is meaningless to
the new control server.

Note the headscale API key defaults to a 90d expiry. When it lapses
headplane stops listing nodes with no obvious cause -- `headscale apikeys
list` shows the date.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

secrets/neptun.yaml

@@ -2,10 +2,10 @@ darman_password: ENC[AES256_GCM,data:7G2Hgh13TxI6ugw2ebp9UtLTQ7HRC/hrCga0FmZo8h8
 authentik_secret_key: ENC[AES256_GCM,data:qLrAWBywlMqT6D3FYDqE9I/5Ep+zDVu9ns9TA4UVOBSQ1uFGEj01TU9norqPf12pi9/Qs32mVzm5BqDG259DxdGT9DZVQc03QVwiIQYtmWo=,iv:OVCIxIP1Xv+nHmYsrxaPgYWQiwzVPUe8pnbyMBVAuoI=,tag:+ywkwPqkY1Dkx1R5cUJ7PA==,type:str]
 authentik_bootstrap_email: ENC[AES256_GCM,data:OmqpKAiiFyS/rytnHYRZ,iv:VXiPV5VfduC/IW+E3gDlNAeE+hr+IZ9W7Ty6Npuu59Y=,tag:rjvTHnBxN/pMvpQC5W9S6Q==,type:str]
 authentik_bootstrap_password: ENC[AES256_GCM,data:QPCY0ni3jBQY5HyK+vRlyT4YTEo=,iv:41u1Jf+WYksPUY4pvKdHQA1RHW21GAfdVDRuQ7XtdYc=,tag:SYmzv26GbE1kwleXyKLG4Q==,type:str]
-tailscale_authkey: ENC[AES256_GCM,data:CBMidfdilBn1HP3TAu9TCOpuwPnzVQ/3OGCsf0vhFd8=,iv:V4UdZBPyzH8NkiXV40CxLdnfkCv5oG6xEQbNSmpmrmI=,tag:h8R2AIaFXgPycMIP8NyHVA==,type:str]
+tailscale_authkey: ENC[AES256_GCM,data:t8oKG+oSZrGF1Xb2YX7qWxo/z/dfsq/56kah/cvIdfQihuOSWNuMEWDcph1wlRCgRmNhQE8oqbO61m8xNQuOn+bNHsAEmh9GO9dt+uFuRKdwXJ2vM0nA+Q==,iv:6aq6buNvJ+Y0AUWBLNCdsl+svGGlXzpn5J3Oy7dPDys=,tag:T/lwzHUtyvcbjbKbu6jWeA==,type:str]
 headplane_cookie_secret: ENC[AES256_GCM,data:oXYRG4z16u6HS7zXoWrV2q/HL2o24n4UwVXnQvqBmbY=,iv:itAiy/w6ue4VzqO5xYnvSYN3uCLLmu52dvAAxZ2pCGc=,tag:MEFP171GpSQpAqUFsWY+VA==,type:str]
-headplane_oidc_client_secret: ENC[AES256_GCM,data:v86GLehXAI4Ol2ZxjtdtB1aDau0qsm68HBz3Iu4HjySPEi9jpg==,iv:EwtrNGKyVYcZg8AnD87EpHpmp0odeBXi1PM/9uUe+ko=,tag:VATaEMNxt5pnmgAHV13rLw==,type:str]
-headplane_headscale_api_key: ENC[AES256_GCM,data:pb2ipeI4rkTXMQMG6hbkSU7OBLcpYJ2/a+9TgSA7PAfL2tTFoDWico8=,iv:j3FkiixUbT+6oLREKP21jQGFFUUU2KqX/ym2xQCeM0k=,tag:ZulMJDpaM1c81yT/LWNWgA==,type:str]
+headplane_oidc_client_secret: ENC[AES256_GCM,data:RiEESz1WHYH/smlJKmKFpPoF5HRYp8gHJoKqc49xRRuU9WnQCnmETie/68u37sSVniQmQZSOmXxdmvuuJgP5LMcPdkrQmQE+QX80RQhtTVvg2AhqRaK4V+qfQleD/aJjoIHojeM3UBUi4kYOhDJF0FFTP+qR4oitH6W8/2jxRsc=,iv:hXquOglPhRv+QTVRw5fkY7BWuwLtJxK5tNERGBOOmt8=,tag:2KczveRWoq7iTOdwjO+AUw==,type:str]
+headplane_headscale_api_key: ENC[AES256_GCM,data:KcwcprV100wfAkn+YM4+1oTfXkmyeAMAbXNpQKf2iIq0VxwqVep+fORrKmHiwDViciDoyxdMiT4scGlmd4vQRsWEHdDpkuH7MRHYu0hQepE3rSSQAMbK,iv:NEhmi2hiOE+uSIRZ4uXOK1UGpN+FQx/NpooWzTgwik8=,tag:KcPsD4gp51ERaFwgfA0BrQ==,type:str]
 caddy_acme_email: ENC[AES256_GCM,data:j+iPz4lt0Gqs2SKHTS53,iv:DQNfcpYy2v93sKeCvXzLOoBhAo0PjZrxHgFD1oVqYu8=,tag:1yPH/2cW/IiRi9lT8dELEg==,type:str]
 sops:
     age:
@@ -27,7 +27,7 @@ sops:
             Wptkf76aP9UpjhgNkxzedRebQPB7ti+UiVqCvLVimtuHcsm/NJPcRg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1hp72xyx2cnd05937e4eww95g5kdtn0wsf9j2nypw330pa69gfdxqn0lpkp
-    lastmodified: "2026-07-20T07:03:51Z"
-    mac: ENC[AES256_GCM,data:jWjdbICvAycAGEkl7r1rdTNfr62Xn4re1pJZU+4IifGW67fSRE0SN99lXCTj1B+WmhchzqBCf42n5D4c5dgQXo51bvWttjayRsUaqA9Hk/5T7QvFdjiNWbXpKsku1qe7VhoxhqzVoNXy/l9LvJTWYTRTStg3RYEmX0XpmbPIsCU=,iv:qCHahmqoHve0bejlssie6kA8zAABkwHV8gBF5hD8ab0=,tag:4MvjJ33QrDRfd4vYK7V7iw==,type:str]
+    lastmodified: "2026-07-20T08:15:48Z"
+    mac: ENC[AES256_GCM,data:yDiCTDaIwMCXZfzE4khI7AHNoYi3AHFX+nSXtioNRqLEOu1fBCA3OqHpzTi4Cskv2o7r9nlxx5AGPM+2d3bSHkXW7SJk680IMA/XzfDIKGU6A7+3NDt14/PgxOvPeVTfNWwlWIW9tXPtTVJmnoItTzPsxcLO3OyfbbO+vZhj/j4=,iv:xeqYTLjG0B6yCWoke0lulHetVNlShmw7Nm+8mmwOZ5I=,tag:JUEqRfEprzGMGoGsXp9rKQ==,type:str]
     unencrypted_suffix: _unencrypted
     version: 3.13.1