homepage: function-first layout + fleet label sweep

Reorganize the gethomepage dashboard from site-based (PFI-ANA, ESH, NH3)
to function-first grouping (Monitoring, AI Systems, Apps, Media, Games,
Infra-<site>, Service Networking). Canonical config now tracked in
configs/homepage/ with Plex/Jellyfin widget keys moved to env
substitution.

Label sweep across fleet compose files:
  - beszel, dozzle, backrest -> Monitoring
  - rest-server-ana -> Service Networking

Healthcheck fixes (previous wget/curl paths broke on distroless +
--private-repos 401):
  - beszel hub:    /beszel health --url ...
  - beszel agent:  /agent health (newly added)
  - rest-server:   nc -z localhost 8000 (TCP probe)

Group name originally "Wiring / Plumbing" collapsed to single-word group
on homepage's parser; renamed to "Service Networking" everywhere.

configs/homepage/bookmarks.yaml

@@ -0,0 +1,43 @@
+# https://gethomepage.dev/latest/configs/bookmarks
+
+- UltraSeedbox:
+  - Control Panel:
+    - abbr: CP
+      icon: si-bittorrent
+      href: http://cp.ultra.cc/
+      description: Ultraseedbox Control Panel
+  - FileZilla:
+    - abbr: fz
+      icon: si-filezilla
+      href: http://10.0.50.154:5800
+      description: FTP Client
+  - ruTorrent:
+    - abbr: rt
+      icon: si-bittorrent
+      href: https://lkraven.hebe.usbx.me/rutorrent/
+      description: ruTorrent Client
+  - Sonarr:
+    - abbr: sr
+      icon: si-sonarr
+      href: https://lkraven.hebe.usbx.me/sonarr/
+      description: TV Shows
+  - Radarr:
+    - abbr: rr
+      icon: si-radarr
+      href: https://lkraven.hebe.usbx.me/radarr/
+      description: Movies
+  - Bazarr:
+    - abbr: br
+      icon: mdi-subtitles
+      href: https://lkraven.hebe.usbx.me/bazarr/
+      description: Subtitles
+  - Sabnzbd:
+    - abbr: nz
+      icon: mdi-newspaper
+      href: https://lkraven.hebe.usbx.me/sabnzbd
+      description: Newz Client
+  - Seedsync:
+    - abbr: sy
+      icon: mdi-download-box
+      href: http://10.0.50.51:8800/dashboard
+      description: Sync Client