fix: improve llmwiki search integration

scripts/stop-backend.ps1

@@ -0,0 +1,20 @@
+. "$PSScriptRoot\env.ps1"
+
+$PidFile = Join-Path $PidDir "backend.pid"
+if (-not (Test-Path -LiteralPath $PidFile)) {
+    Write-Host "Backend is not running (no pid file)."
+    exit 0
+}
+
+$rawPid = Get-Content -LiteralPath $PidFile | Select-Object -First 1
+$processId = 0
+if (-not [int]::TryParse([string]$rawPid, [ref]$processId) -or -not (Get-Process -Id $processId -ErrorAction SilentlyContinue)) {
+    Remove-Item -LiteralPath $PidFile -Force -ErrorAction SilentlyContinue
+    Write-Host "Backend is not running (stale pid file removed)."
+    exit 0
+}
+
+Write-Host "Stopping backend (pid $processId)..."
+Stop-ProcessTree -ProcessId $processId
+Remove-Item -LiteralPath $PidFile -Force -ErrorAction SilentlyContinue
+Write-Host "Backend stopped."