homepage: three-tab layout (Main/Infra/Plumbing) + 4-column grids

Flat-list layout didn't scale well once auto-discovery filled Apps and
Service Networking with a dozen+ cards each. Splits the dashboard:

  Main     — Monitoring, AI Systems, Apps, Media, Games, UltraSeedbox
  Infra    — three per-site hardware groups
  Plumbing — Service Networking (dockge x5, traefik, adguard, etc.)

Row counts set to 4 columns on dense groups so they render as grids
rather than vertical walls.

configs/homepage/settings.yaml

@@ -22,22 +22,49 @@ quicklaunch:
 showStats: false
 statusStyle: ""
 
-# Function-first layout. Site-partitioned Infra groups keep the inventory
-# together without mixing app/infra concerns.
+# Function-first layout, three-tab split:
+#   Main     - daily-use apps, inference, media, bookmarks
+#   Infra    - hardware, hypervisors, BMCs (per site)
+#   Plumbing - toolchain that's running but rarely clicked
+#
+# Row counts target ~4-per-row so dense groups (Apps, Service Networking)
+# read as a grid instead of an endless column.
 layout:
   Monitoring:
+    tab: Main
     style: row
-    columns: 3
+    columns: 4
   AI Systems:
+    tab: Main
+    style: row
+    columns: 4
+  Apps:
+    tab: Main
+    style: row
+    columns: 4
+  Media:
+    tab: Main
     style: row
     columns: 3
-  Apps:
-  Media:
   Games:
+    tab: Main
   UltraSeedbox:
+    tab: Main
     style: row
     columns: 3
   Infra - ANA:
+    tab: Infra
+    style: row
+    columns: 4
   Infra - NH3:
+    tab: Infra
+    style: row
+    columns: 4
   Infra - ESH:
+    tab: Infra
+    style: row
+    columns: 4
   Service Networking:
+    tab: Plumbing
+    style: row
+    columns: 4