perf: speed up desktop startup and unify theme-aware branding (#596)

* fix: unify startup logo and loading theme behavior

Show desktop window immediately with animated splash logo
Align splash/logo colors with selected app theme and default themes
Keep auth loading state on full-screen logo without size jump
Make project SVG icons follow active app theme
Use the active theme foreground color for project icons discovered from favicons
Apply server-side SVG color overrides for currentColor icons via icon request params
Keep non-SVG project icons unchanged while preserving existing fallback behavior

* perf: speed up desktop startup and unify loading logo visuals

Desktop startup now shows UI sooner while backend boot continues in background
Startup host probing uses a faster local path with safer remote fallback retries
OpenChamber logo cube highlights now match splash screens consistently

* fix: keep macOS traffic-light buttons in the correct position on load

Stop native window title updates on macOS during app initialization
Prevent title bar relayout that reset custom traffic-light positioning

* fix: recover missing providers and agents after fast startup

Retries provider/agent loading when connection is up but core config is still empty
Prevents cold-start state where models/agents appear only after manual project switch
Keeps startup responsive with throttled background recovery in app bootstrap

packages/ui/src/components/auth/SessionAuthGate.tsx

@@ -6,6 +6,7 @@ import { isDesktopShell, isVSCodeRuntime } from '@/lib/desktop';
 import { syncDesktopSettings, initializeAppearancePreferences } from '@/lib/persistence';
 import { applyPersistedDirectoryPreferences } from '@/lib/directoryPersistence';
 import { DesktopHostSwitcherInline } from '@/components/desktop/DesktopHostSwitcher';
+import { OpenChamberLogo } from '@/components/ui/OpenChamberLogo';
 
 const STATUS_CHECK_ENDPOINT = '/auth/session';
 
@@ -61,12 +62,10 @@ const AuthShell: React.FC<{ children: React.ReactNode }> = ({ children }) => (
   </div>
 );
 
-const LoadingScreen: React.FC<{ message?: string }> = ({ message = 'Preparing workspace…' }) => (
-  <AuthShell>
-    <div className="w-full max-w-sm rounded-3xl border border-border/40 bg-card/90 px-6 py-5 text-center shadow-none backdrop-blur">
-      <p className="typography-ui-label text-muted-foreground">{message}</p>
-    </div>
-  </AuthShell>
+const LoadingScreen: React.FC = () => (
+  <div className="flex min-h-screen items-center justify-center bg-background text-foreground">
+    <OpenChamberLogo width={120} height={120} isAnimated />
+  </div>
 );
 
 const ErrorScreen: React.FC<ErrorScreenProps> = ({ onRetry, errorType = 'network', retryAfter }) => {