Add welcome dashboard as default view

Replace the All Services grid as the landing view with a
Nextcloud-style welcome dashboard:

- Greeting (time-of-day), "Welcome to Your Sovereign Digital &
  Financial Life" headline, version + role meta line
- Status cards: Systems Operational, Network (LAN/WAN/hostname),
  Bitcoin sync progress with ETA, and available-updates card
- Calm drifting orb background animation (transform-only,
  disabled under prefers-reduced-motion)
- Services grid stays mounted but hidden until the user browses
  (Browse button, search, or a nav category); Dashboard nav item
  returns to the welcome view
- Move role badge and autolaunch preference out of the sidebar;
  autolaunch toggle now lives in the Systems Operational modal
- Remove LAN/WAN chip from the topbar; IPs live on the Network card

app/sovran_systemsos_web/static/js/tiles.js

@@ -273,6 +273,7 @@ async function loadNetwork() {
 async function checkUpdates() {
   try {
     var data = await apiFetch("/api/updates/check");
+    window._lastUpdateCheck = data;
     if (typeof markUpdateChecked === "function") markUpdateChecked();
     var hasUpdates = !!data.available;
     var updateStatus = data.status || "idle";