fix: EventLog handle leak and StreamWriter crash in WinBGP CLI

[Daymarvi]

Summary

Fix two resource management issues in WinBGP.ps1 (CLI):

1. EventLog handle leak in Write-Log

[System.Diagnostics.EventLog]::new() implements IDisposable but was never disposed after writing events with AdditionalFields. In a 24/7 service context, this causes gradual handle exhaustion.

Fix: Wrap EventLog usage in try/finally with Dispose().

2. StreamWriter crash on unconnected pipe in Send-PipeMessage

StreamWriter was created before pipe.Connect(). If the connection failed or timed out, Dispose() on the StreamWriter would throw an unhandled .NET exception because the underlying pipe was never connected.

Fix: Move StreamWriter creation after successful pipe.Connect(1000).

Testing

Tested on production server my.server.net.

Functional tests

Command	Result
WinBGP.ps1 -Status	✅ Running
WinBGP.ps1 -BGPStatus	✅ 3 routes displayed (route1, route2, route3) all up
WinBGP.ps1 -RouteName my.server.net -StartMaintenance	✅ Success
WinBGP.ps1 -RouteName my.server.net -StopMaintenance	✅ Success
WinBGP.ps1 -RouteName my.server.net -StopRoute	✅ Success
WinBGP.ps1 -RouteName my.server.net -StartRoute	✅ Success

Handle leak test

$svcPid = (Get-CimInstance Win32_Service -Filter "Name='WinBGP'").ProcessId
Get-Process -Id $svcPid | Select-Object HandleCount
1..50 | ForEach-Object { & "C:\Program Files\WinBGP\WinBGP.ps1" -Status }
Get-Process -Id $svcPid | Select-Object HandleCount

Metric	Value
HandleCount before (PID 1264)	214
50x consecutive -Status calls	All returned Running
HandleCount after	214
Result	✅ No handle leak