Phase 7: polish — overview health, reduced-motion, mobile, a11y, copy-ids

- Overview health hero derives from subsystem probes when the backend gives no
  overall status, so it never says "Unknown" next to an all-Healthy Subsystems
  card (the audit's most jarring contradiction). Home error copy now uses the
  Phase-2 describeError instead of raw backend strings.
- Global prefers-reduced-motion guard (transitions, loops, aurora field) +
  motion-reduce on the sidebar width transition.
- Mobile: content reserves a top row (pt-16 md:p-6) so the floating hamburger
  never overlaps the page H1.
- A11y: collapsed rail items get an explicit aria-label.
- Monitoring: disk "busiest mount" tile shows the % as the value and the long
  mount path as a truncated caption, so it no longer clips mid-word.
- New CopyId component (click-to-copy UUIDs), wired into Profile.

Typecheck 36→36, 24-route sweep clean. Remaining items (lib a11y labels,
table aria-sort, dev-only monitoring data) noted in the spec.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

app/routes/profile.tsx

@@ -5,6 +5,7 @@ import { ArcadiaError, useArcadiaClient } from "@crema/arcadia-core-client"
 import { AlertBanner } from "@crema/feedback-ui"
 
 import { AppShell } from "~/components/layout/app-shell"
+import { CopyId } from "~/components/copy-id"
 import { Avatar, AvatarFallback, AvatarImage } from "~/components/ui/avatar"
 import { Badge } from "~/components/ui/badge"
 import { Button } from "~/components/ui/button"
@@ -357,9 +358,11 @@ export default function ProfileRoute() {
               </span>
               {account ? (
                 <>
-                  <span className="text-xs text-muted-foreground">
-                    Tenant <code className="font-mono">{account.tenant_id}</code> ·
-                    ID <code className="font-mono">{account.id}</code>
+                  <span className="flex flex-wrap items-center gap-1.5 text-xs text-muted-foreground">
+                    Tenant
+                    <CopyId value={account.tenant_id} label="tenant id" dataAction="profile-copy-tenant-id" />
+                    · ID
+                    <CopyId value={account.id} label="account id" dataAction="profile-copy-account-id" />
                   </span>
                   <span className="text-xs text-muted-foreground">
                     Last sign-in{" "}