feat: send text to named sessions with draft protection and listener isolation

- chat send and listener-smoke accept --session; defaults remain File Transfer Assistant.
- Reject existing drafts, reacquire the send control after input changes, and require a
  fresh message fingerprint for confirmation without retrying failed sends.
- Test-NamedTextSend sends the same text twice and verifies distinct confirmed fingerprints;
  Test-NamedListeners -SendMarkers verifies per-window own events exactly once with zero
  cross-session events. Note export now requires a unique fresh owned note window and keeps
  repeated paragraphs. 97 Core tests pass; real-machine validated.

scripts/windows/Test-NamedTextSend.ps1

@@ -0,0 +1,23 @@
+param(
+    [Parameter(Mandatory=$true)][string]$Executable,
+    [Parameter(Mandatory=$true)][string]$OutputDirectory,
+    [string]$Session='消息测试专用群组'
+)
+$ErrorActionPreference='Stop'
+$exe=(Resolve-Path $Executable).Path
+if(Test-Path $OutputDirectory){throw 'Use a fresh evidence directory.'}
+$directory=(New-Item -ItemType Directory $OutputDirectory).FullName
+$marker='wx-agent-repeat-'+[Guid]::NewGuid().ToString('N')
+$results=@()
+for($i=0;$i -lt 2;$i++){
+    $result=(& $exe chat send --session $Session --text $marker --timeout 30 | Out-String) | ConvertFrom-Json
+    $exitCode=$LASTEXITCODE
+    $results+=@{ExitCode=$exitCode;Fingerprint=$result.Fingerprint;Error=$result.error;Message=$result.message}
+    if($exitCode -ne 0){break} # Never retry a failed send.
+}
+$success=($results.Count -eq 2 -and $results[0].ExitCode -eq 0 -and $results[1].ExitCode -eq 0 -and
+    $null -ne $results[0].Fingerprint -and $null -ne $results[1].Fingerprint -and
+    $results[0].Fingerprint -ne $results[1].Fingerprint)
+@{Success=$success;Results=$results;AttemptedSends=$results.Count;BinarySha256=(Get-FileHash $exe -Algorithm SHA256).Hash} |
+    ConvertTo-Json -Depth 5 | Set-Content "$directory\summary.json" -Encoding UTF8
+if(!$success){exit 1}