Fix Backend service PYTHONPATH for shared module imports

Fixed critical runtime error where backend service couldn't import
shared modules (ModuleNotFoundError: No module named 'database').

Changes:
- Updated Install-BackendFirstTime: Set PYTHONPATH to shared directory
  instead of parent directory
- Added Fix-BackendPythonPath.ps1: Quick fix script for existing
  installations

The backend imports 'from database.oracle_pool' which requires the
database module to be in PYTHONPATH. Previously PYTHONPATH pointed to
C:\inetpub\wwwroot\roa2web but the database module is located at
C:\inetpub\wwwroot\roa2web\shared\database. Now PYTHONPATH correctly
points to the shared directory.

For existing installations, run Fix-BackendPythonPath.ps1 as Administrator
to update the service configuration without reinstalling.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

deployment/windows/scripts/ROA2WEB-Console.ps1

@@ -624,7 +624,10 @@ function Install-BackendFirstTime {
         & nssm set $Config.BackendServiceName Description $Config.BackendServiceDescription
         & nssm set $Config.BackendServiceName Start SERVICE_AUTO_START
         & nssm set $Config.BackendServiceName AppDirectory $Config.BackendPath
-        & nssm set $Config.BackendServiceName AppEnvironmentExtra "PYTHONPATH=$($Config.InstallPath)"
+
+        # Set PYTHONPATH to shared directory for module imports
+        $sharedPath = Join-Path $Config.InstallPath "shared"
+        & nssm set $Config.BackendServiceName AppEnvironmentExtra "PYTHONPATH=$sharedPath"
 
         # Set logging
         $stdoutLog = Join-Path $Config.LogsPath "backend-stdout.log"