fix(analytics): stop UMAMI_NOT_CONFIGURED returning 409 — caused dev server hangs

Root cause of recurring dev server hangs:
/api/v1/website-analytics threw CodedError('UMAMI_NOT_CONFIGURED') which
rendered as HTTP 409. React Query default-retries on 4xx (we set retry=1
globally), so every page render fired the umami queries → 409 →
retry → 409. Each request queried system_settings to resolve umami
credentials. Six analytics widgets on the /website-analytics page +
two on the dashboard glance tile × 2 (initial + retry) = 16 system_settings
queries on first paint. Combined with React Query refetching on mount,
the postgres pool (max=20) saturated and the server appeared hung.

Fix: return 200 with `{ data: null, notConfigured: true }` instead of
4xx. Not-configured is a steady empty state, not a transient error —
no retry loop. Updated WebsiteGlanceTile (hides itself) and
WebsiteAnalyticsShell (renders configure-umami CTA) to check the new
notConfigured flag.

Also includes from in-flight work: package.json dev script binds
0.0.0.0 so iPhone on LAN can reach the dev server, and BrandedAuthShell
uses fixed/inset-0 + flex to lock the login surface to the viewport so
iOS Safari doesn't rubber-band-scroll the card.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/dashboard/website-glance-tile.tsx

@@ -27,10 +27,9 @@ export function WebsiteGlanceTile() {
 
   // Hide the tile entirely if Umami isn't configured - this dashboard is
   // for sales, not for prompting the operator into integration setup.
-  if (
-    stats.data?.error === 'umami_not_configured' ||
-    active.data?.error === 'umami_not_configured'
-  ) {
+  // The API surfaces `notConfigured: true` on a 200 response so React
+  // Query doesn't retry-loop (a prior 409-throw caused server hangs).
+  if (stats.data?.notConfigured || active.data?.notConfigured) {
     return null;
   }