perf(desktop): reduce CPU/GPU overhead in Tauri shell

- SSH monitor: adaptive polling 2s→10s after stabilization, cheap TCP
  probe before expensive SSH subprocess check
- SSH setup: exponential backoff in wait_for_master_ready and
  wait_local_forward_ready (250ms→2s cap)
- Health checks: exponential backoff (100ms→1s / 250ms→2s) instead of
  flat intervals
- Startup recovery poll: cap at 15 retries instead of infinite
- Remove webview log target in release builds (eliminates IPC overhead)
- Set global NO_PROXY env var at startup for all loopback addresses
- Remove reqwest::blocking feature; use raw TCP for sidecar shutdown and
  SSH health checks
- Disable pinch-to-zoom on macOS via WKWebView.setAllowsMagnification
- Add WebView2 browser args on Windows (proxy bypass + disable unused
  UI features)
- Add Cargo release profile: thin LTO, codegen-units=1, strip
- Extract apply_platform_window_config for consistent window setup
- Add vibrancy toggle in Appearance settings (macOS desktop only) with
  solid background fallback when disabled

packages/ui/src/components/sections/openchamber/OpenChamberVisualSettings.tsx

@@ -19,7 +19,7 @@ import {
     SelectTrigger,
     SelectValue,
 } from '@/components/ui/select';
-import { isDesktopShell, isVSCodeRuntime, isWebRuntime } from '@/lib/desktop';
+import { isDesktopShell, isVSCodeRuntime, isWebRuntime, desktopSetVibrancy } from '@/lib/desktop';
 import { useDeviceInfo } from '@/lib/device';
 import { usePwaDetection } from '@/hooks/usePwaDetection';
 import { updateDesktopSettings } from '@/lib/persistence';
@@ -209,6 +209,7 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
     } = useThemeSystem();
 
     const [themesReloading, setThemesReloading] = React.useState(false);
+    const [vibrancyEnabled, setVibrancyEnabled] = React.useState(true);
     const [chatRenderPreviewTick, setChatRenderPreviewTick] = React.useState(0);
     const reportUsage = useUIStore(state => state.reportUsage);
     const setReportUsage = useUIStore(state => state.setReportUsage);
@@ -219,6 +220,28 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
         void updateDesktopSettings({ reportUsage: enabled });
     }, [setReportUsage]);
 
+    const isMacDesktop = React.useMemo(() => {
+        if (!isDesktopShell()) return false;
+        if (typeof navigator === 'undefined') return false;
+        return /Macintosh|Mac OS X/.test(navigator.userAgent || '');
+    }, []);
+
+    React.useEffect(() => {
+        if (!isMacDesktop) return;
+        const stored = localStorage.getItem('desktopVibrancy');
+        if (stored !== null) {
+            setVibrancyEnabled(stored !== 'false');
+        }
+    }, [isMacDesktop]);
+
+    const handleVibrancyChange = React.useCallback((enabled: boolean) => {
+        setVibrancyEnabled(enabled);
+        localStorage.setItem('desktopVibrancy', String(enabled));
+        document.documentElement.classList.toggle('no-vibrancy', !enabled);
+        void desktopSetVibrancy(enabled);
+        void updateDesktopSettings({ desktopVibrancy: enabled });
+    }, []);
+
     const shouldAnimateChatPreview = isSettingsDialogOpen
         && (visibleSettings ? visibleSettings.includes('chatRenderMode') : true);
 
@@ -503,6 +526,24 @@ export const OpenChamberVisualSettings: React.FC<OpenChamberVisualSettingsProps>
                                 </Tooltip>
                             </div>
 
+                            {isMacDesktop && (
+                                <div className="flex items-center gap-2 py-1.5">
+                                    <Checkbox
+                                        checked={vibrancyEnabled}
+                                        onChange={handleVibrancyChange}
+                                        ariaLabel="Toggle window vibrancy"
+                                    />
+                                    <div className="flex min-w-0 flex-col">
+                                        <span className="typography-ui-label text-foreground">
+                                            Window vibrancy
+                                        </span>
+                                        <span className="typography-meta text-muted-foreground">
+                                            Translucent window background. Disabling may reduce energy usage.
+                                        </span>
+                                    </div>
+                                </div>
+                            )}
+
                             {showPwaInstallNameSetting && (
                                 <div className="py-1.5 space-y-1.5">
                                     <div className="flex min-w-0 flex-col">