feat: migrate Open WebUI to PostgreSQL on glyph

Configure Open WebUI to use the local PostgreSQL instance instead of
SQLite for improved reliability and backup support.

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

Author: stackptr

hosts/glyph/services/db.nix

@@ -12,12 +12,16 @@
       port = 5432;
       max_connections = 150;
     };
-    ensureDatabases = ["atticd" "pocketid"];
+    ensureDatabases = ["atticd" "open-webui" "pocketid"];
     ensureUsers = [
       {
         name = "atticd";
         ensureDBOwnership = true;
       }
+      {
+        name = "open-webui";
+        ensureDBOwnership = true;
+      }
       {
         name = "pocketid";
         ensureDBOwnership = true;
@@ -27,6 +31,6 @@
 
   services.postgresqlBackup = {
     enable = true;
-    databases = ["atticd" "pocketid"];
+    databases = ["atticd" "open-webui" "pocketid"];
   };
 }

hosts/glyph/services/open-webui.nix

@@ -27,6 +27,7 @@
       OAUTH_ALLOWED_ROLES = "users, admins";
       OAUTH_ADMIN_ROLES = "admins";
       ENABLE_LOGIN_FORM = "false";
+      DATABASE_URL = "postgresql:///open-webui?host=/run/postgresql";
     };
   };
 }