feat(homepage): add The High Seat (SVOS board, nh3-dev:8770)

Requested by svos-dev relaying the operator, 2026-09-22. Reversible work, so
the relay is fine to act on without escalating.

Manual services.yaml entry rather than container labels, because SVOS is a
user-level systemd unit (svos.service) on nh3-dev and nh3-dev is NOT one of
the five hosts in docker.yaml -- Homepage has no Docker API to discover it
through. Same reason the Booth, WhereTF, talk and the infra-hermes seat are
listed by hand, and the comment says so at the entry.

⚠ siteMonitor is "/" deliberately. There is no /api/health on this service:
that path 404s, and a monitor pointed at it would report the board
permanently down while it serves perfectly. svos-dev flagged it and it is
verified here -- / returns 200 and serves the SPA (<title>The High Seat</title>).

Group is Apps, which exists in settings.yaml's layout with tab: Main. An
invented group name gets no tab and renders on ALL tabs, which is how
Scriberr's "AI Systems" leaked across the whole dashboard in August.

Icon mdi-monitor-dashboard is my choice -- svos-dev explicitly did not guess
at one and offered to take a different suggestion.

Verified in a browser, not just in the API: the card renders in Apps with a
green site-monitor at 28 ms.

stacks/homepage/conf/services.yaml

@@ -43,6 +43,19 @@
       icon: /images/talk.svg
       siteMonitor: https://talk.nh3.phasefinal.com:8092/
       description: TTS chat surface — type or speak, a fleet voice answers
+  # Manual entry — SVOS is a user-level systemd service on nh3-dev
+  # (svos.service), and nh3-dev is not one of the hosts in docker.yaml, so
+  # Homepage cannot discover it from labels. Requested by svos-dev relaying
+  # the operator, 2026-09-22.
+  # ⚠ siteMonitor is "/" ON PURPOSE. There is NO /api/health on this service —
+  # that path 404s, and a monitor pointed at it would show the board
+  # permanently down while it serves perfectly. The root returns 200 and the
+  # SPA. (svos-dev hit exactly this reading its own logs; verified here.)
+  - The High Seat:
+      href: http://10.100.10.50:8770/
+      icon: mdi-monitor-dashboard
+      siteMonitor: http://10.100.10.50:8770/
+      description: SVOS mission control — live fleet telemetry across Claude Code sessions, and the conversation with Miranda
   # Manual entry — WhereTF is a user-level systemd service on nh3-dev (Bun,
   # like the Booth), so Homepage can't auto-discover it.
   - WhereTF: