Migrate from oswaldtheotter.lan to lan.oswaldtheotter.net

Moves the search domain onto a real delegated subdomain and points DNS at
Technitium's new address on the atlashorizon VLAN (192.168.7.2) instead of
1.1.1.1 / its 192.168.0.x address. The S3 state backend endpoint follows
the same rename.

Drops the manual .lan records and the bookstack Caddy proxy along with the
old zone: those hosts are served under the new domain now, and leaving
them would have recreated the retired zone on the next apply.

Co-Authored-By: Claude Opus 5 <[email protected]>

backend.tf

@@ -10,7 +10,7 @@ terraform {
     key    = "infra/terraform.tfstate"
     region = "garage"
 
-    endpoint         = "http://s3.oswaldtheotter.lan:30188"
+    endpoint         = "http://s3.lan.oswaldtheotter.net:30188"
     use_path_style = true
 
     skip_credentials_validation = true