chore(secrets): remove per-host beszel-token secrets

Five files contained only beszel-token and are deleted entirely.
nix-cache.yaml retains cache-priv-key; beszel-token removed from it.
The universal token in secrets/common.yaml replaces all of these.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

secrets/nix-cache.yaml

@@ -1,4 +1,3 @@
-beszel-token: ENC[AES256_GCM,data:meuzUP/6wCssJDVTgbC0XwiLZPMGyDl55HEIiON9xOXCD9k6,iv:TDqWcp+8Mxd8wN09r5otQRQXq3XTeQphaTWxvvuLTAs=,tag:cRPZQGlwB/dTguBAheWPQg==,type:str]
 cache-priv-key: ENC[AES256_GCM,data:6vQKIf7eS0WNL2Eptoi4VWr18SRMZfN/H/aFUUtXdMYQY5LLyBp2EHRKqZcGFuh1nZhUdAxUztq/CVXx+QFxKW+ElHxCxUSp0QqI1fdSkBkKZb8hlit5SoX9JtLzZGg0HBNM3nJu,iv:0J+xmrPJhInHhFR/c41ACjuTfaIoMkQFSfbL2KkgFa8=,tag:f4s9Szs5oprVVRSyXaX48A==,type:str]
 sops:
     age:
@@ -38,7 +37,7 @@ sops:
             IqA477+noQ/Rjrszb2hEvxID7keogcDUWMWQzQvdMc22+3mvAr9qIg==
             -----END AGE ENCRYPTED FILE-----
           recipient: age1jlltcv5jcnm40z5k0q6hv053k2rqpqvemtuecdwn527uw8uqz4es3x7m68
-    lastmodified: "2026-07-19T23:30:21Z"
-    mac: ENC[AES256_GCM,data:kLGE2xawQT7mx+sfw68hmGk5nCEGiEjZrqTEl9B1dtQmTrMwmoVr/1RISi4LfJrwxy31mDgff4lcIL4wIJuM373uk3X8j4RNyYQNTfKEkORT6r8NHeepNs267O77pKGd7OmcM4MT/BqOnB8ELS7Wlf2ect7CAlvUUVyc8icxgZE=,iv:EYLDsHYHZ1XOQXafOTqHHWpk/OBNq/R6IJnOBYV33E4=,tag:thxrCPC5oGvDjhK7Dz87YA==,type:str]
+    lastmodified: "2026-07-29T01:59:11Z"
+    mac: ENC[AES256_GCM,data:/nbcfause6G6F8IvMoyPZtkWS1XRLAivhwTFu6y5P0Mm0eCcO6M7/rgioN9dngKzPXrCUl3Dx/EvhrrWKe2/Saq9WEOFgvS2V05pTRbQgYjuugVzW2paPq1fgmoDYNjHz2yFYWAovbIFtjVxMR9tmcASMTe6r/FocvMXbFCJh7Y=,iv:n3KoaPPtDhWK8mxJNJRk7WPVUUNR59nZSA8JyysWNDc=,tag:tYhkNXsj2ohVjHkvxife2w==,type:str]
     unencrypted_suffix: _unencrypted
-    version: 3.13.1
+    version: 3.13.3