build-installer: run ISCC from the .iss directory (fixes Gitea runner)

Some ISCC builds reject deeply-nested absolute .iss paths (the runner
runs out of %SystemRoot%\System32\config\systemprofile\.cache\act\...)
with a misleading 'The system cannot find the path specified.' before
touching any source files. Push-Location to the .iss directory and
pass the bare filename - same effect, no path quirk.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

scripts/build-installer.ps1

@@ -53,15 +53,58 @@ if ($LASTEXITCODE -ne 0) { throw 'service publish failed' }
     -c $Configuration -r win-x64 --self-contained false -o $publishGui | Out-Host
 if ($LASTEXITCODE -ne 0) { throw 'GUI publish failed' }
 
-# 2. Compile installer.
+# 2. Pre-flight: confirm every source path the .iss references exists, and
+#    surface the longest path so MAX_PATH issues are obvious in the log.
+function Show-SourcePath($label, $path, [switch]$Recursive) {
+    if (-not (Test-Path $path)) { Write-Warning "MISSING $label : $path"; return }
+    $items = if ($Recursive) {
+        Get-ChildItem $path -Recurse -File -ErrorAction SilentlyContinue
+    } else {
+        Get-ChildItem $path -File -ErrorAction SilentlyContinue
+    }
+    $count   = ($items | Measure-Object).Count
+    $longest = ($items | Measure-Object -Maximum -Property { $_.FullName.Length }).Maximum
+    Write-Host ("  {0,-30} files={1,-5} longestPath={2,-5} root={3}" -f $label, $count, $longest, $path)
+}
+
+Write-Host ""
+Write-Host "--- pre-flight: source paths the .iss will read ---" -ForegroundColor Cyan
+Show-SourcePath 'publish\service'        $publishSvc                              -Recursive
+Show-SourcePath 'publish\gui'            $publishGui                              -Recursive
+Show-SourcePath 'scripts'                (Join-Path $repoRoot 'scripts')
+Show-SourcePath 'scripts\examples'       (Join-Path $repoRoot 'scripts\examples') -Recursive
+Show-SourcePath 'docs'                   (Join-Path $repoRoot 'docs')             -Recursive
+Show-SourcePath 'resources'              (Join-Path $repoRoot 'resources')
+Show-SourcePath 'README.md (file)'       (Join-Path $repoRoot 'README.md')
+
+$lpe = (Get-ItemProperty 'HKLM:\SYSTEM\CurrentControlSet\Control\FileSystem' `
+            -Name LongPathsEnabled -ErrorAction SilentlyContinue).LongPathsEnabled
+Write-Host "  LongPathsEnabled (HKLM): $lpe"
+Write-Host ""
+
+# 3. Compile installer.
 $iscc = Find-InnoCompiler
 $iss = Join-Path $repoRoot 'installer\webhook-server.iss'
 $dist = Join-Path $repoRoot 'dist'
 New-Item -ItemType Directory -Path $dist -Force | Out-Null
 
 Write-Host "Compiling installer with $iscc"
-& $iscc "/DAppVersion=$version" $iss
-if ($LASTEXITCODE -ne 0) { throw 'Inno Setup compile failed' }
+# Run ISCC from the .iss directory with just the bare filename. When invoked
+# with a deeply-nested absolute path on the act-runner host (under
+# %SystemRoot%\System32\config\systemprofile\...), ISCC sometimes prints a
+# generic "The system cannot find the path specified." before it touches any
+# source files. cd-ing first sidesteps it.
+$issDir  = Split-Path $iss -Parent
+$issName = Split-Path $iss -Leaf
+Push-Location $issDir
+try {
+    Write-Host "  cwd=$issDir"
+    & $iscc "/DAppVersion=$version" $issName
+    $exit = $LASTEXITCODE
+} finally {
+    Pop-Location
+}
+if ($exit -ne 0) { throw "Inno Setup compile failed (exit $exit)" }
 
 $out = Get-Item (Join-Path $dist "WebhookServer-Setup-$version.exe")
 Write-Host ""