feat(sprint4-6): quality, reliability, perf baseline

Sprint 4 — qualità codice:
- scripts/_Common.psm1: New-CISessionOption, Resolve-VmrunPath, Invoke-Vmrun
- PSScriptAnalyzerSettings.psd1: project-wide PSSA rules (security + formatting)
- Remove-BuildVM.ps1: SupportsShouldProcess (-WhatIf support)
- Invoke-RemoteBuild.ps1, Get-BuildArtifacts.ps1: use New-CISessionOption from module
- New-BuildVM.ps1: use Resolve-VmrunPath + Invoke-Vmrun from module

Sprint 5 — affidabilità:
- Backup-CITemplate.ps1: stop runner, timestamped VMDK backup, prune old, restart
- Watch-RunnerHealth.ps1: auto-restart act_runner, cooldown 3/h, EventLog + webhook
- Register-CIScheduledTasks.ps1: add CI-RunnerHealth task (every 15 min)

Sprint 6 — perf baseline:
- Set-TemplateSharedFolders.ps1: idempotent VMX editor for NuGet/pip shared folders
- Invoke-RemoteBuild.ps1: -UseSharedCache injects NUGET_PACKAGES + PIP_CACHE_DIR in guest
- Measure-CIBenchmark.ps1: times clone/start/IP/WinRM/destroy, appends to benchmark.jsonl

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

scripts/Register-CIScheduledTasks.ps1

@@ -5,7 +5,7 @@
     Registers Windows Scheduled Tasks for CI system maintenance.
 
 .DESCRIPTION
-    Creates or updates two tasks under the \CI\ task folder:
+    Creates or updates four tasks under the \CI\ task folder:
 
       CI-CleanupOrphans   — Runs Cleanup-OrphanedBuildVMs.ps1 every 6 hours
                             and at host startup. Destroys stale build VMs
@@ -17,7 +17,15 @@
                             Purges old artifact and log directories per the
                             configured retention window.
 
-    Both tasks run as SYSTEM with highest privilege. Idempotent: safe to re-run
+      CI-DiskSpaceAlert   — Runs Watch-DiskSpace.ps1 every 15 minutes.
+                            Writes an Event Log warning and optional webhook
+                            when CI drive free space falls below 50 GB.
+
+      CI-RunnerHealth     — Runs Watch-RunnerHealth.ps1 every 15 minutes.
+                            Auto-restarts act_runner if stopped; rate-limited
+                            to 3 restarts per hour before requiring manual fix.
+
+    All tasks run as SYSTEM with highest privilege. Idempotent: safe to re-run
     after updating the scripts — existing tasks are overwritten (-Force).
 
 .PARAMETER ScriptRoot
@@ -155,4 +163,36 @@ if (-not (Test-Path $diskScript -PathType Leaf)) {
     }
 }
 
+# ── Task 4: CI-RunnerHealth ───────────────────────────────────────────────────
+$healthScript = Join-Path $ScriptRoot 'Watch-RunnerHealth.ps1'
+if (-not (Test-Path $healthScript -PathType Leaf)) {
+    Write-Warning "Script not found — skipping CI-RunnerHealth: $healthScript"
+} else {
+    $healthAction = New-ScheduledTaskAction `
+        -Execute  $psExe `
+        -Argument "-NoProfile -NonInteractive -ExecutionPolicy Bypass -File `"$healthScript`""
+
+    # Every 15 minutes indefinitely
+    $health15min = New-ScheduledTaskTrigger -Once -At '00:00' `
+        -RepetitionInterval (New-TimeSpan -Minutes 15)
+
+    $healthSettings = New-ScheduledTaskSettingsSet `
+        -ExecutionTimeLimit (New-TimeSpan -Minutes 5) `
+        -MultipleInstances  IgnoreNew `
+        -StartWhenAvailable
+
+    if ($PSCmdlet.ShouldProcess('CI-RunnerHealth', 'Register/update scheduled task')) {
+        Register-ScheduledTask `
+            -TaskName   'CI-RunnerHealth' `
+            -TaskPath   $taskPath `
+            -Action     $healthAction `
+            -Trigger    $health15min `
+            -Principal  $principal `
+            -Settings   $healthSettings `
+            -Description 'Auto-restarts act_runner service if stopped; rate-limited to 3 restarts/h (Local CI/CD System)' `
+            -Force | Out-Null
+        Write-Host "[Register] CI-RunnerHealth registered (every 15 min, max 3 restarts/h)." -ForegroundColor Green
+    }
+}
+
 Write-Host "`n[Register] Done. Verify with: Get-ScheduledTask -TaskPath '\CI\' | Format-Table TaskName, State" -ForegroundColor Cyan