feat(ui): full frontend redesign to the Sentry-style design system (#86)

* feat(ui): full frontend redesign to the Sentry-style design system

Replace the legacy UI with the dark, mono-accent design language from
design/23-sentry.html across every non-canvas surface.

- PlatformShell: fixed 252px sidebar with grouped nav (Platform /
  Operate / Workspace), brand mark, user card, and a topbar with
  search (Cmd+K palette), env badge, upgrade, notifications, and
  theme toggle; mobile collapses to a top bar with horizontal nav
- New shared component kit in shared/components/sentry.tsx:
  SPageHead, SStat, SCard, STable, SSection, SPill, Ticks, Seg,
  GhostBtn/QuietBtn/IconBtn, status tone helpers
- New DashboardPage at / — stats row, per-node CPU chart with
  1h/24h/7d ranges, resource usage tick strips, anomaly box,
  node summary table, recent deployments and project cards;
  real API data with demo-mode fixtures
- Landing page moved to /landing and rebuilt: live host telemetry
  window, install strip, feature grid, template catalog, docs
- Every page (Projects, Templates, Builds, Databases, HA,
  Operations, Activity, Security, Usage, Docs, People, Settings,
  Audit Logs, Webhooks, Admin, NodeDetail, ServiceDetail, auth,
  setup, not-found) migrated to the new kit and tokens
- Nav active state resolves by longest matching href
- Canvas internals intentionally untouched — separate pass

Verified: tsc --noEmit, eslint, vite build, Playwright walkthrough
of every route at desktop and mobile widths (demo + live session).

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

* fix(ui): deep audit pass — palette navigation, crash fix, honest badges

- CommandPalette: full route navigation, project deep-links fetched on
  open, Create group only where onAddService is wired, dead Connect
  items removed, decorative kbd hints dropped; workspace passes its own
  view targets
- NodeDetailPage crash: container status arrives as a Docker state
  object, not a string — flattened in listAgentContainers and guarded
  at render for persisted-cache payloads
- env badge reflects import.meta.env.MODE instead of hardcoded
  'production'
- Relative times capped: >1y or future timestamps render 'n/a'/'—'
  (zero-time heartbeats no longer show 739898d ago)
- Post-auth and setup redirects land on / (dashboard is the index)

Generated with [Devin](https://devin.ai)

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

* fix(ui): use SPageHead actions prop, satisfy tsc -b literal types

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

---------

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

app/frontend/src/shared/components/Card.tsx

@@ -77,12 +77,12 @@ export function CardHeader({ title, description, icon, action, className = '', .
     <div className={`flex items-start justify-between gap-4 ${className}`} {...props}>
       <div className="flex items-start gap-3">
         {icon && (
-          <div className="w-10 h-10 rounded-xl flex items-center justify-center flex-shrink-0 ring-1 ring-white/5" style={{ background: 'rgba(255,255,255,0.07)' }}>
+          <div className="w-10 h-10 rounded-xl flex items-center justify-center flex-shrink-0 ring-1 ring-[var(--tint-05)]" style={{ background: 'var(--tint-07)' }}>
             {icon}
           </div>
         )}
         <div>
-          <h3 className="text-lg font-semibold text-[var(--text-primary)] tracking-tight">{title}</h3>
+          <h3 className="font-headline text-base font-semibold text-[var(--text-primary)] tracking-tight">{title}</h3>
           {description && (
             <p className="text-sm text-[var(--text-secondary)] mt-0.5">{description}</p>
           )}