feat: improve Linux bootable USB stability and user experience

- Enhanced Live USB environment detection and support
- Added troubleshooting guide (TROUBLESHOOTING.md)
- Added installation test script (test-installation.sh)
- Improved error handling in PowerShell scripts
- Better network retry logic for downloads
- Enhanced desktop integration for Live environments
- Added detailed improvements summary (IMPROVEMENTS_SUMMARY.md)
- Updated README with troubleshooting links

Key improvements:
1. Auto-detection of Live USB environment (boot=casper)
2. Additional dependency installation for Live environments
3. Network download retry mechanism (3 attempts)
4. Smart browser opening with fallback instructions
5. Comprehensive installation validation script
6. Detailed fault diagnosis and recovery guide

bootable/1-prepare-usb.ps1

@@ -56,15 +56,48 @@ if (Test-Path $VentoyZip) {
     Write-Host "[INFO] Ventoy archive already cached, skipping download." -ForegroundColor Green
 } else {
     Write-Host "[INFO] Downloading Ventoy v${VentoyVersion}..." -ForegroundColor Yellow
+    
+    # 检查网络连接
+    try {
+        $netTest = Test-NetConnection -ComputerName "github.com" -Port 443 -WarningAction SilentlyContinue
+        if (-not $netTest.TcpTestSucceeded) {
+            Write-Host "[WARN] Network connection to GitHub may be unstable." -ForegroundColor Yellow
+        }
+    } catch {
+        Write-Host "[WARN] Network check failed, continuing anyway..." -ForegroundColor Yellow
+    }
+    
     try {
         [Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
         $ProgressPreference = 'SilentlyContinue'
-        Invoke-WebRequest -Uri $VentoyUrl -OutFile $VentoyZip -UseBasicParsing
-        Write-Host "[OK]   Download complete." -ForegroundColor Green
+        
+        # 设置超时和重试
+        $retryCount = 0
+        $maxRetries = 3
+        $downloaded = $false
+        
+        while ($retryCount -lt $maxRetries -and -not $downloaded) {
+            try {
+                if ($retryCount -gt 0) {
+                    Write-Host "[INFO] Retry $retryCount of $maxRetries..." -ForegroundColor Yellow
+                    Start-Sleep -Seconds 2
+                }
+                
+                Invoke-WebRequest -Uri $VentoyUrl -OutFile $VentoyZip -UseBasicParsing -TimeoutSec 30
+                $downloaded = $true
+                Write-Host "[OK]   Download complete." -ForegroundColor Green
+            } catch {
+                $retryCount++
+                if ($retryCount -eq $maxRetries) {
+                    throw $_
+                }
+            }
+        }
     } catch {
-        Write-Host "[ERROR] Download failed: $_" -ForegroundColor Red
+        Write-Host "[ERROR] Download failed after $maxRetries attempts: $($_.Exception.Message)" -ForegroundColor Red
         Write-Host "        You can manually download from:" -ForegroundColor Yellow
         Write-Host "        https://github.com/ventoy/Ventoy/releases" -ForegroundColor Yellow
+        Write-Host "        Save to: $VentoyZip" -ForegroundColor Yellow
         Read-Host "Press Enter to exit"
         exit 1
     }