fix(ui): UI/UX pass — connectivity probe, mobile overflow, real metrics, deep links (#85)

Found during a browser-driven audit of the whole app:

- connectivity banner showed permanently: pingServer() resolved
  undefined, which React Query treats as an error; returns boolean now
- Vite dev proxy now forwards /health so the probe actually measures
  the backend, and the API target is env-overridable (VITE_API_PROXY)
- auth-session removed from the persisted query cache — stale sessions
  no longer rehydrate into a false signed-in flash
- workspace Observability tab no longer shows fabricated random metrics
  ("87K Active User", fake performance/speed-test cards); the dashboard
  now aggregates real per-service metrics (CPU, memory, network, instances)
- service detail tabs write ?section= so tab state is shareable/deep-linked
- Security page auto-selects the first project instead of rendering blank
- People page user-creation form no longer overflows its card
  (minmax(0,1fr) grid tracks; same fix on env-var rows)
- page padding is responsive (px-4 sm:px-8) so mobile keeps content width;
  Projects header wraps instead of clipping the "+ new project" button
- template deploy modal shows a loading state while the session resolves
  instead of flashing the sign-in prompt
- audit log table strips the CIDR suffix from displayed IPs
- docs list excerpts no longer repeat the document title
- activity filter placeholder "Search search…" → "Search events…"
- workspace view tabs get more room: ⌘K button now waits for lg:

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Co-authored-by: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

app/frontend/src/features/operations/pages/OperationsPage.tsx

@@ -88,7 +88,7 @@ export function OperationsPage() {
           <Loader2 size={20} className="animate-spin text-[var(--text-muted)]" />
         </div>
       ) : (
-        <div className="w-full px-8 py-6 space-y-6">
+        <div className="w-full px-4 py-6 sm:px-8 space-y-6">
           <div className="grid grid-cols-2 md:grid-cols-4 gap-4">
             <div className="panel-soft p-4">
               <p className="text-xs uppercase tracking-wider text-[var(--text-muted)]">In flight</p>