feat(clan): data-mesher + dm-pull-deploy wiring 🌊

Stage 4e-a of the clan migration. Set up signed-file gossip
(data-mesher, experimental, clan-core) and pull-based NixOS deploy
(dm-pull-deploy, experimental, clan-community) across both servers.

- sunken-ship is the data-mesher bootstrap node + dm-pull-deploy push
  role; phantom-ship joins via /dns/sunken-ship.clan/tcp/7946/... — the
  hostname resolves via /etc/hosts (clanHostsModule) to sunken-ship's
  ZT IPv6 since we don't run a DNS server for the clan domain.
- Both machines run the dm-pull-deploy default role with
  action="switch": they watch /var/lib/data-mesher/files/home/
  dm_pull_deploy/target and nixos-rebuild switch against the pushed
  git+…?rev=…&narHash=… flake ref on each change.
- Signing keys (shared + per-host status) generated via clan vars
  generate, ran on sunken-ship because data-mesher isn't packaged for
  aarch64-darwin.

The legacy dotfiles-rebuild timer stays installed as a fallback until
dm-pull-deploy is proven; a smart push timer on sunken-ship (calls
dm-send-deploy only when origin/main moves) comes next.

vars/per-machine/sunken-ship/dm-pull-deploy-status-key/signing.key/secret

@@ -0,0 +1,18 @@
+{
+	"data": "ENC[AES256_GCM,data:E1Kds+yeaAIqu+az9a4QwyXb9yxIcq31IjrqqwLBnILp8oEIbPjaKbbCS/C8bbom9BeYixfeAlmo8iDE3IIdbq5W2vf/JNsLSulKF+9KnwA86aq1aNeI7akZGcs9Nvmly4lEUjCQH+rF3kGPNj/ji4uvNxm7FLU=,iv:LbOQMEBhSvwAWipVmF+NHW34CKXZla/YHYWPwySb/+M=,tag:EMHcLXPzUOABzy1+EGZw0Q==,type:str]",
+	"sops": {
+		"age": [
+			{
+				"recipient": "age1g6y8gvcampqj5y3yzdajke2h5n7k6ckdg6a424cghy5325px7cmqjmmd28",
+				"enc": "-----BEGIN AGE ENCRYPTED FILE-----\nYWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSAwQVUxSGdkWFNZdm92OTFM\nZnZCeERNSEtWWnpiV0hLS2lsNzNCYkdBUDBJCm1kSzY1eFBGakVXVEV5TVFpdEts\nTkNiQmNHcnZZaTE1NnlVaCtFelF3clUKLS0tIHljYkM1QXVwKzlNNjJOOXlCT0FL\ncmdqcjRzeE8vR3VaU2JCcVdxTXJJd1kKR637rNaq3aceU7NxwBves13/2foYGzje\ncqnfkDARHDltiykBW0QXOfy8ws0XOrCXu5snd414WNeyGxgHuygXJQ==\n-----END AGE ENCRYPTED FILE-----\n"
+			},
+			{
+				"recipient": "age1zy3q73pujauyajgfqwu0pnyy8732lzwvw87tu7p2xg3xuzaujc2qh6ql77",
+				"enc": "-----BEGIN AGE ENCRYPTED FILE-----\nYWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBZSTRBV1FGSkEzNHpoOHRE\nQU1rR0p5VVBtWXV0eXJ2L0ZWeW1iS3FDb21rCkpudnZiMjQrbEVzSWY1SEVhZk5v\naFV6NktldUkzaFlVQmdKNlFTalVoUEEKLS0tIDdrN2Vzejd6a3ByblJKcnhRMytR\nZm9DMFBFWSs1Z0IzeXlnWlVNWi9zbmMKULDR3ES98A2+BAXHuKvgod6IRQS9jbAK\nkGo8k2taP1+UhEIJbWY3WdfF621Eg/Ojc6+IQofrcrHTL+mu2MDN+g==\n-----END AGE ENCRYPTED FILE-----\n"
+			}
+		],
+		"lastmodified": "2026-04-20T09:37:04Z",
+		"mac": "ENC[AES256_GCM,data:YyEnzCEsCF2E5TuB9cbYaaMpDGqkCGYQ/fnS/+r/VsXINF9fVTRNbN8nYGWMsJvv3YOYkbGzfQXk0ydAEDYoQ7mFMjqtQjcLJqACkWLknkr366/CQ4eFnIvUMpiritjzPDX/8K7RFkCsWgtfIrKgKtCeoRkjbmxsKeP3gZWKqAI=,iv:G5zNZlVKmCS6297whHQpnSJXckwPS9pDpNcpFiAu8FE=,tag:VGaPrFF0swxqXTTsqZzgug==,type:str]",
+		"version": "3.12.2"
+	}
+}