feat: migrate Grafana to PostgreSQL on glyph (#364)

Configure Grafana on spore to use centralized PostgreSQL on glyph via
Tailscale instead of local SQLite. Add grafana database, user, and
backup to glyph's PostgreSQL configuration.

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" "open-webui" "pocketid"];
+    ensureDatabases = ["atticd" "grafana" "open-webui" "pocketid"];
     ensureUsers = [
       {
         name = "atticd";
         ensureDBOwnership = true;
       }
+      {
+        name = "grafana";
+        ensureDBOwnership = true;
+      }
       {
         name = "open-webui";
         ensureDBOwnership = true;
@@ -31,6 +35,6 @@
 
   services.postgresqlBackup = {
     enable = true;
-    databases = ["atticd" "open-webui" "pocketid"];
+    databases = ["atticd" "grafana" "open-webui" "pocketid"];
   };
 }

hosts/spore/services/grafana.nix

@@ -43,6 +43,13 @@
         auto_login = false;
         skip_org_role_sync = true;
       };
+      database = {
+        type = "postgres";
+        host = "glyph.rove-duck.ts.net:5432";
+        name = "grafana";
+        user = "grafana";
+        ssl_mode = "disable";
+      };
       security = {
         admin_user = "corey@zx.dev";
         admin_email = "corey@zx.dev";