Redesign UI like Driver Navigator + fix CMD window

UI changes:
- Top title bar with logo, app name, and system status LED
- Toolbar with 4 icon tabs: Scan, Drivers, Download, System
- Scan page with computer SVG illustration, stats, and big SCAN NOW button
- Step indicator bar: Scan Devices > Review Drivers > Install Updates
- Driver list with per-row progress bars, Download + Install buttons
- "Update All Drivers" CTA bar at bottom when outdated drivers found
- Windows Update tab with pending/installed sections
- System Info tab with resource bars
- Footer with About/Help buttons

Backend fixes:
- Add cmdutil.HiddenCommand() using CREATE_NO_WINDOW (0x08000000)
- All PowerShell subprocesses now run without visible console window
- Build with -ldflags "-H windowsgui" to hide main CMD window

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/drivers/drivers.go

@@ -2,9 +2,10 @@ package drivers
 
 import (
 	"encoding/json"
-	"os/exec"
 	"strings"
 	"time"
+
+	"github.com/mumur/driver-booster/internal/cmdutil"
 )
 
 type Driver struct {
@@ -63,7 +64,7 @@ func (s *Scanner) enumDriversPnP() []Driver {
 	psScript := `
 Get-CimInstance Win32_PnPSignedDriver | Where-Object { $_.DeviceName -ne $null } | Select-Object -First 100 DeviceName, DeviceClass, Manufacturer, DriverVersion, DriverDate, InfName, IsSigned, Status | ConvertTo-Json -Compress
 `
-	out, err := exec.Command("powershell", "-NoProfile", "-Command", psScript).Output()
+	out, err := cmdutil.HiddenCommand("powershell", "-NoProfile", "-Command", psScript).Output()
 	if err != nil {
 		return []Driver{}
 	}