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/data-mesher-node-identity/identity.cert/machines/sunken-ship

@@ -0,0 +1 @@
+../../../../../../sops/machines/sunken-ship

vars/per-machine/sunken-ship/data-mesher-node-identity/identity.cert/secret

@@ -0,0 +1,18 @@
+{
+	"data": "ENC[AES256_GCM,data:HUvMiGEnMxlfYnnxX5RgZlw7SdETT/4BCkU7J1LhCeXH/BBN9PcT0jqhepyQ+3ybksk2zOTbxb0uiIodeaoSUKJM+jO1OKRElwtJObAVFPYw65x4TpH2n3j8JTWyIj9OdHFh7sXYGFK92GUsSGDWoZBV++AfzKa/KHw//8Zzy4ol3dgx6JPPQjvTvKIPoTaCre43RcB013UUdO2VRdh8x27KgybtlT8HXb6lAIRpuUS2cXCfbPW4E3ayinyKjVJ2iLUsmaSGSl8SltTk5GdGAYLEVTITH0Y1GNliZ04ENNuGdHVF5VlCIpuLcon9,iv:I2NUjIU5lUe8xpPMc1bYF0sHQ1pwlOO4Gz9ox/KCnrs=,tag:iqzJpTXMUdqUyp98hM/blw==,type:str]",
+	"sops": {
+		"age": [
+			{
+				"recipient": "age1g6y8gvcampqj5y3yzdajke2h5n7k6ckdg6a424cghy5325px7cmqjmmd28",
+				"enc": "-----BEGIN AGE ENCRYPTED FILE-----\nYWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBBU2ZyRjRURkNjSjcyaENQ\ncVZ5d2tKTlJVemdRaFZZUURzbEZGVFNGRlFFClY5Y29pRCtSelhlY3VlV0x6eXJx\nNmF1T1YwVjdjL3ZSaGZUK0I3cHQzc0EKLS0tIGkzVE9mcldIbWpicU5YeEZjbHVG\nQ0dJQXd1cENLeFNtaUxHM3EzTDRHSFkKeXjt+AnbcQqWTpOw3TWJTbIH+Mu0q/Du\noE3Lv8b3LcVFPb/OQz3tNvd7FftjEbH6yArcLJfKz8YcKSG6/X+H9w==\n-----END AGE ENCRYPTED FILE-----\n"
+			},
+			{
+				"recipient": "age1zy3q73pujauyajgfqwu0pnyy8732lzwvw87tu7p2xg3xuzaujc2qh6ql77",
+				"enc": "-----BEGIN AGE ENCRYPTED FILE-----\nYWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBHeThUamlhRGVnb0pHUUQ3\nTWtwV3QvZXF6ZmRyVkRrNXg4dVgwZk96MWlNClAxMWhua29JRkpCeUNXdE14ODNv\ndk9DVVVsaTJiQ29IL1BHdERHWUhVSDAKLS0tIEg1bTRSRklaTFBhN2FLd3NIek1i\na1ZEQ1FxYzhzUmhMQmVlQjJYZ2M4MWMKhUBYaEA09xLoc0GAShctrGPFUE4YUGGk\nYW86mPh4uudivrxs6CAhH0GVB7qwVtc9EGEw8bVA2STdNnCzr0JmMg==\n-----END AGE ENCRYPTED FILE-----\n"
+			}
+		],
+		"lastmodified": "2026-04-20T09:37:04Z",
+		"mac": "ENC[AES256_GCM,data:yvwDLQ1unefwvtlad7/QBqKnWIsU3hALVB3ia6vYl5wnaRZgycE1IHrDLrHVV20ANAAs1gRKcZYUAAKLYKo4SqduBJgVSf3Hjk9t5VRjcBvRRFizwFbBa4rtWZMBrJS0cV99me6FoLioFLA+zGonRmmkiCEbWbBvSZdf1J04ixw=,iv:mD42aLv2IY8Dvt9qfTBQKH2ZHeI4537tRMlA8AXdyVk=,tag:Up/RwgH+fsJIpwPFzM6B9g==,type:str]",
+		"version": "3.12.2"
+	}
+}

vars/per-machine/sunken-ship/data-mesher-node-identity/identity.cert/users/danny

@@ -0,0 +1 @@
+../../../../../../sops/users/danny