Fix first real VSTO build, add sender account selection, polish deploy

First live build against real Visual Studio/VSTO tooling surfaced two
issues in the hand-written AddIn scaffold: ThisAddIn derived from the
wrong base type (OutlookAddIn is an interface, not the concrete
OutlookAddInBase class), and VSTO Application projects cannot build
without a signed ClickOnce manifest, so SignManifests is now on with a
throwaway self-signed test certificate. Both Core/Core.Tests/AddIn now
build clean and Core.Tests passes.

Also: mail always sent from Outlook's default account with no way to
pick a different one (e.g. a shared mailbox) - added a "From account"
setting (Session.Accounts dropdown in SettingsForm, SendUsingAccount in
MailSender). And added deploy/ with both a local ClickOnce publish
script (real install/uninstall via Windows Apps, no manual registry
editing) and a manual registry sideload fallback for scripted rollouts.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

outlook-bulk-sender/deploy/install-addin.reg

@@ -0,0 +1,12 @@
+Windows Registry Editor Version 5.00
+
+; Sideload регистрация BulkArchiveMailer для текущего пользователя.
+; Перед применением скопируйте всю папку bin\Release\ в C:\Tools\BulkArchiveMailer\
+; (или другой стабильный путь - тогда поправьте "Manifest" ниже под свой путь).
+; Подробности и типичные проблемы - outlook-bulk-sender/docs/BUILD.md.
+
+[HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\BulkArchiveMailer.AddIn]
+"Description"="Массовая рассылка архивов ssh-access-tui"
+"FriendlyName"="BulkArchiveMailer"
+"Manifest"="file:///C:\\Tools\\BulkArchiveMailer\\BulkArchiveMailer.AddIn.vsto|vstolocal"
+"LoadBehavior"=dword:00000003

outlook-bulk-sender/deploy/publish-clickonce.ps1

@@ -0,0 +1,103 @@
+<#
+.SYNOPSIS
+    Rebuilds the ClickOnce installer for BulkArchiveMailer.AddIn (Способ А
+    in ../docs/BUILD.md) without hand-typing the long MSBuild -t:Publish
+    command each time.
+
+.DESCRIPTION
+    Wraps:
+
+        MSBuild.exe BulkArchiveMailer.AddIn\BulkArchiveMailer.AddIn.csproj -t:Publish -p:Configuration=Release
+            -p:PublishUrl=<repo>\BulkArchiveMailer.AddIn\bin\Release\app.publish\
+            -p:InstallUrl=<repo>\BulkArchiveMailer.AddIn\bin\Release\app.publish\
+            -p:PublishDir=bin\Release\app.publish\ -p:UpdateEnabled=false
+
+    MSBuild.exe is located via vswhere.exe first (works across VS
+    installs/versions/editions); if vswhere itself isn't found, falls back
+    to the fixed path this repo has been built with so far
+    (D:\VS2022\MSBuild\Current\Bin\amd64\MSBuild.exe). Pass -MSBuildPath to
+    override either lookup explicitly.
+
+.PARAMETER MSBuildPath
+    Explicit path to MSBuild.exe. Skips both the vswhere lookup and the
+    hardcoded fallback when supplied.
+
+.EXAMPLE
+    .\deploy\publish-clickonce.ps1
+
+.EXAMPLE
+    .\deploy\publish-clickonce.ps1 -MSBuildPath 'C:\Program Files\Microsoft Visual Studio\2022\Community\MSBuild\Current\Bin\amd64\MSBuild.exe'
+#>
+[CmdletBinding()]
+param(
+    [string]$MSBuildPath
+)
+
+$ErrorActionPreference = 'Stop'
+
+# Repo layout: this script lives in outlook-bulk-sender\deploy\, the
+# project lives one level up in outlook-bulk-sender\BulkArchiveMailer.AddIn\.
+$repoRoot = Split-Path -Parent $PSScriptRoot
+$projectPath = Join-Path $repoRoot 'BulkArchiveMailer.AddIn\BulkArchiveMailer.AddIn.csproj'
+$publishDir = Join-Path $repoRoot 'BulkArchiveMailer.AddIn\bin\Release\app.publish\'
+
+if (-not (Test-Path $projectPath)) {
+    throw "Project file not found: $projectPath"
+}
+
+function Resolve-MSBuildPath {
+    param([string]$explicitPath)
+
+    if ($explicitPath) {
+        if (-not (Test-Path $explicitPath)) {
+            throw "-MSBuildPath was given but does not exist: $explicitPath"
+        }
+        return $explicitPath
+    }
+
+    $vswhere = 'C:\Program Files (x86)\Microsoft Visual Studio\Installer\vswhere.exe'
+    if (Test-Path $vswhere) {
+        $found = & $vswhere -latest -requires Microsoft.Component.MSBuild -find 'MSBuild\**\Bin\MSBuild.exe' 2>$null |
+            Select-Object -First 1
+        if ($found -and (Test-Path $found)) {
+            Write-Host "Using MSBuild found via vswhere: $found"
+            return $found
+        }
+        Write-Warning 'vswhere.exe ran but did not report a usable MSBuild.exe - falling back to the fixed path.'
+    } else {
+        Write-Warning "vswhere.exe not found at '$vswhere' - falling back to the fixed path."
+    }
+
+    $fallback = 'D:\VS2022\MSBuild\Current\Bin\amd64\MSBuild.exe'
+    if (-not (Test-Path $fallback)) {
+        throw "Could not locate MSBuild.exe via vswhere, and the fallback path does not exist either: $fallback. Pass -MSBuildPath explicitly."
+    }
+
+    Write-Host "Using fallback MSBuild path: $fallback"
+    return $fallback
+}
+
+$msbuild = Resolve-MSBuildPath -explicitPath $MSBuildPath
+
+Write-Host "Publishing $projectPath (Release, local ClickOnce, updates disabled) to:`n  $publishDir"
+
+& $msbuild $projectPath `
+    -t:Publish `
+    -p:Configuration=Release `
+    -p:PublishUrl=$publishDir `
+    -p:InstallUrl=$publishDir `
+    -p:PublishDir=$publishDir `
+    -p:UpdateEnabled=false `
+    -m
+
+if ($LASTEXITCODE -ne 0) {
+    throw "MSBuild -t:Publish failed with exit code $LASTEXITCODE"
+}
+
+$vstoPath = Join-Path $publishDir 'BulkArchiveMailer.AddIn.vsto'
+if (Test-Path $vstoPath) {
+    Write-Host "`nDone. Installer manifest: $vstoPath"
+    Write-Host "Copy the whole 'app.publish' folder to the operator's machine and double-click the .vsto file there (see docs/BUILD.md, Способ А)."
+} else {
+    Write-Warning "Publish reported success but $vstoPath was not found - check the MSBuild output above."
+}

outlook-bulk-sender/deploy/uninstall-addin.reg

@@ -0,0 +1,8 @@
+Windows Registry Editor Version 5.00
+
+; Полностью убирает регистрацию BulkArchiveMailer из Outlook для текущего
+; пользователя (обратное к install-addin.reg). Закройте Outlook перед
+; применением. После применения можно вручную удалить папку с файлами
+; плагина (например, C:\Tools\BulkArchiveMailer\), если она больше не нужна.
+
+[-HKEY_CURRENT_USER\Software\Microsoft\Office\Outlook\Addins\BulkArchiveMailer.AddIn]