chore(secrets): Phase 4 — remove stale sops.yaml anchors and re-encrypt

Remove four stale age key anchors from .sops.yaml that correspond to
non-lxc build-type variants that were never deployed (or are now
superseded by their lxc-* counterparts):

  &docker   → superseded by &lxc-docker (active running host)
  &server   → superseded by &lxc-server (active running host)
  &nix-cache → superseded by &lxc-nix-cache (active running host)
  &nix-minimal → superseded by &lxc-minimal (active running host)

Also remove the secrets/docker.yaml creation_rules block entirely since
that file does not exist.

Re-encrypt secrets/common.yaml, secrets/nix-cache.yaml, and
secrets/server.yaml with sops updatekeys to drop the stale recipients.
The four removed keys can no longer decrypt these files.

Update README.md and CLAUDE.md to clarify that deployed lxc-* hosts
now use clan vars (vars/per-machine/<target>/openssh/) rather than the
gitignored host-keys/ directory.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01B2EJ4qTsM5KUqhS5c3GAwx

secrets/server.yaml

@@ -3,47 +3,38 @@ sops:
     age:
         - enc: |
             -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBxT3dteUY4T0VxaUljbFQ3
-            UjBSSjZCdWpmTGpDS1BabjV4R0lyOE9haEZrCjlmSXllWTB0L0E5N1MrTk1IODR2
-            bXZuamN3Yjk0THdka1dBZE5uS05DRkEKLS0tIDBkTmtpU1JoNmN0cHd0WGVseERt
-            eEcrOXdFaUNBQ3g2aytYM3RwM1dBd00KiSRrzv6eRMdIzZaUlC6JmsZV6rYJgrre
-            vbI1KHtNZKetx81+MmElIKog6kMtTPtI7MVpMwCCPO8zAU5Uh7jSoQ==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBZeDQyNFh3dm1YZ2FTMjdK
+            cDBWcDE2a1c1S0s1enhWRnVuMlVJc0gyTXk0CmxWNkRJMDhkeGpRTGltaitnVkZS
+            a3Q5TW4zYm5Ja2FETEhJcGF0N2ZKbmcKLS0tIDN0a1FqRGNOY3Y1UWxvUU8zWU1m
+            bE9DVzZESG1HTEhVWUdJOTF0bDhRVGcKP6OoyDAGLB9jQ69jpFyho5eaeK9XtZgN
+            RlSJpBm2Jo19h/crpH9AWXUAIG0BWueyr8mwBu12cQdFIU3IyZT6gg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1njap586hc0q43kr03g6c8eqhdsmk8zcafkl3f83xwlc2gqhlmfgs4tmwad
         - enc: |
             -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBmWUMyVGpua25ZZ1FRZ21p
-            a1lxdS85d2JzOXBLVC92MjlNbTZOOVgvSlhNCm12WmtIb3dQanNkanBCU2t4VTd2
-            TGFidEpSR254Qm5jTVF0WnprcjJWVncKLS0tIGwzRWZkY25rZXE4Q2VETU93Mno3
-            aGN6MmcvVkRGZkJQN3V1ak90T3BMVFEKLcEdqKQ3SStSdH5vjQ6RH+oA10OLGXad
-            TZE0h435sg/tq/Rff+KWngczFRuq7Yg0KYph8bNAKy6uf+RceZ8Ngg==
-            -----END AGE ENCRYPTED FILE-----
-          recipient: age1ll6hj5ggruetgjwjfnplpn5xtq35uhlcdflksx3xmnjm6s3uad9sz70jkf
-        - enc: |
-            -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBSMG12OTVwdFhnTkFrNmZl
-            UDFLcmJtL2FNejJnWlZYd093MlZmWG04dmdJCkhGLzNGcVQyVVp6SGdISTF0ejhv
-            OVRoQXNlSWZCWDdDMTM0YTFJYlRQd2cKLS0tIHJxVDVscUxEdTV1MGhNVlpWVS8v
-            aWhSNDh1NEZHYzRHeXZNOFRuRzBjazAK2RMK5ylm4uM55fXgrRrY+GeN86ym9wC9
-            JNDcNyxE6H/sZGBZJbFLWKDj+VM9X86j5TFFpnjSrKi2CPOzmzgmKw==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSAwRVFQcHpkQkNlSDhhM1Zp
+            bUZyOFduQXg1cDd6ZlNObFgzL2hmUmJhM1JFCnprMldPQXJNVW10dVRqQTdWcGlv
+            RnBYWWFsaVNrMkJpS0pkOGlQQzlJVVUKLS0tIFNsMEEwZTREZ1lwWFJGdE5YSVVU
+            ZEZ1bVpFMEQ5N0g0L2RacUpLMWQrVDQKxPzq6f960purgAmUJw6IZnZSnhkzNE8r
+            CSrFDowKTZI2KRdCtQ5fGhEoWO0ZPgVNxYV0KH7JBttylcpRLm6r5w==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1sweerhrga9yf8x6sv0apz4ed4g48rnlcq34rpv20t0rcelwgpgeqwvndzz
         - enc: |
             -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBLRHdnSkFZc0NYYnQvd0Mz
-            a3dmTHdLN3Z6UGh3SkpBMGhtSHRJTC9SblJnCmFuOTJGSE5nOWIwQWRNV010RkMw
-            VnBJVXdtVm1tL2d2bXFWWnBtamVRVk0KLS0tIDNHUndvTnd2Z2VSb3dxVUFUcTcz
-            ODVDRzBBclhPZjJDYVkwWktMUENSek0KnTFdNMa8L5uPLvl2aJLvaZEUTbGwL+va
-            wLnWhf/bm8edMeyfWcpS2uHMSDpozWfqObrrP23LCrDBf/B7EG+TWw==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSB0czVoT3ZyYTZhOEQ3RWtR
+            bVl1MW5vNERxUEpmNXV0MGVBRE9ySnBjT3pzCkM2aUVpZjg0SkNVTnRRMlhyMTN6
+            NlFrZDVKV09Yc0tuKzFzR0ZtQ2t6WkkKLS0tIG1mbUNFdHBycS9UOGc2cjNpeHVm
+            NUd1NThRQlZXeG1WbmR5Y3pTYXRKc3MKwSnE+0bGmxOAQUje6jHxuzIIyD6ZAwVz
+            b5AAYwbGRagKj6fimsHBUmi4ohyG1huIGGOU8HiUYpu4PGJgOscztg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1nruncs4l0ufk7yuc4des8p99c0alfndl0lhsws8tycl5pplfp56s30af5f
         - enc: |
             -----BEGIN AGE ENCRYPTED FILE-----
-            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSAyeTJMS1A0eXJnQVcvaVEy
-            VEttdGdMcVIzNlIvclZESkJoTHBZeW1GUVFBCmhmRlBLN3lLdW9TS1JKOW83Yis4
-            dVBGNjdPZXdGYllzN0VyRGFVRFFCMU0KLS0tIEZqN1ljQ0s3TDJYWEEwWk1YVmFs
-            R1l1LzdHUDVvUHQwY1NtZUUxajZkZUkKZv1ejN+LKZqFqDRak5ktFaR3kMPCQeFl
-            q8/DHLFx+1IFChxMGkgstGGmkZdxG4khpYJJXAVNyQsyIW9bjJiqZQ==
+            YWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBlVGRDMWNDZUR6c1VpUjRK
+            WDY3L2lNcWFFcm1UV3RPMjlqYnBGVEJLcFFzCjFxck4wdlp0Wmtzc1RKNS82MXpK
+            ZHBzOGhkc3ZuZUE2UmpUSTgycWdLSGMKLS0tIFUyYjczeUFWU2FyMlBTdzAxMTBE
+            VzhaVzlSL05nZzNmR0ZjNEFPTXYycHcKfiJ0KjdxtLWsXxsWKzAL+H3hYYjHrYO9
+            BjKknq1ZQJM0sB/Tid+GLqDwKi966MQK+AwHF5MqbsHW7eE5bO1nwg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1529taqdwr6t0w7cvzmty0d5y5593wffl0krt48j6uc4u39k56g2qf6ywtp
     lastmodified: "2026-07-19T02:30:40Z"