clanService/phonebox-global: decentralized phone network over yggdrasil

New service alongside phonebox. Boxes get a random 6 digit number
(100000-999999) signed by the machine's yggdrasil key. A serf gossip
cluster on yggdrasil port 7946 exchanges the signed records;
phonebox-sync verifies key -> address derivation and the signature and
writes the number -> address map to /run/phonebox/numbers for the
asterisk dialplan. Any yggdrasil node running the service can reach any
other; clan-core's ygg-input filter is opened for SIP, RTP and gossip.

Includes a two-node VM test proving directory convergence and a call
over yggdrasil. The existing phonebox service is untouched.

modules/clan/phonebox-global/tests/vm/sops/secrets/server-age.key/secret

@@ -0,0 +1,14 @@
+{
+	"data": "ENC[AES256_GCM,data:Sy9T0zEgSGZ/qkz5kaRN2qlH2X+pFRibzb8FpWuknuSI/9lActSG2Loq4LhmhqPGC5MGVkQcz2pcVFI7afUjzDzejfJf4De1ka4=,iv:JNLXguWEwJXR2+WNl0v0nUvkESVAbccfeQSUijKbj2I=,tag:/AAFKncO+B/XmUZYTQnTTw==,type:str]",
+	"sops": {
+		"age": [
+			{
+				"enc": "-----BEGIN AGE ENCRYPTED FILE-----\nYWdlLWVuY3J5cHRpb24ub3JnL3YxCi0+IFgyNTUxOSBqOXJoSXgvcEFXK2hWTlpi\nQWhCdnZPUCt5R2xEWFYxUnpWVlc1ei93TncwCjNKaVB0MFN1VUdheEwyUTBzcmFT\nb0RjTHp2MGE4cWIraCtZME9rQXAvVEkKLS0tIFpiZDhCN0NIY3FWTnlXaFhiMmtC\nTFJMUncvMnFRSEhNdHlhaWozcjlqYWsKLDH1VFG/QS3VIMn6Iwo2NmY5kdBiOPNR\nj4sOY6xBpWP5AiGUypGoX4Bm52gLgW5AdcBRIxxhFOekIv5G8wmRaw==\n-----END AGE ENCRYPTED FILE-----\n",
+				"recipient": "age1qm0p4vf9jvcnn43s6l4prk8zn6cx0ep9gzvevxecv729xz540v8qa742eg"
+			}
+		],
+		"lastmodified": "2026-09-18T02:02:23Z",
+		"mac": "ENC[AES256_GCM,data:DN97Dcpy29IZkBbwFVnMxnUnWYrgLKuvbANabkMCdpOJYgI1msYODltHJlR68Lk8Fmg25sXysvdbJOnc2cMH3pgcKxeyfhdAFwlIXdie1HRtTpZql15RF0fwPBGJjwL9YYubpZU7K4cNflGbjuOCEhp8bQOUYY8Ptd2deiDGGuw=,iv:bxTcKLUu6fcz7JKzStKiakgBeNx7aWCw6M7HolthfEo=,tag:/0nWBkdCPkpcWSpcfY/TfA==,type:str]",
+		"version": "3.13.3"
+	}
+}

modules/clan/phonebox-global/tests/vm/sops/secrets/server-age.key/users/admin

@@ -0,0 +1 @@
+../../../users/admin