fix: apply all FIX-TODO items (P0/P1/P2)

P0 bugs:
- Invoke-CIJob.ps1: skip --depth 1 when $Commit specified (shallow clone
  + checkout specific commit was silently failing)
- Get-BuildArtifacts.ps1: check .Length -eq 0 not rounded sizeKB (false
  fail on artifacts smaller than 50 bytes)
- build-nsis.yml: upgrade upload-artifact v3 -> v4 (v3 deprecated)

P0 security:
- Remove hardcoded default password CIBuild!ChangeMe2026 from all scripts,
  README, TODO; prompt Read-Host -AsSecureString at runtime instead
- Setup-TemplateVM.ps1: replace `net user $u $p /add` (password in argv /
  audit log 4688) with New-LocalUser + local ConvertTo-SecureString
- Prepare-TemplateSetup.ps1: save and restore WSMan AllowUnencrypted +
  TrustedHosts in finally block (was permanently mutating host WinRM config)
- Setup-TemplateVM.ps1: remove duplicate MaxMemoryPerShellMB (winrm set
  + Set-Item both setting same value)

P1 doc (stale Host-Only / VMnet11 era):
- Setup-TemplateVM.ps1: rewrite NETWORK REQUIREMENT block + final steps
  (system uses VMnet8 NAT permanently, not VMnet11 Host-Only)
- Invoke-CIJob.ps1 Phase 1 comment: correct network model
- ARCHITECTURE.md: remove Git from toolchain list (not installed); clarify
  zip-transfer rationale (no PAT in VM, not network isolation)
- BEST-PRACTICES.md: rewrite Step 8 as NAT topology verification

P1 minor:
- Invoke-RemoteBuild.ps1: remove wasted first New-Item (created then
  immediately removed and recreated)
- Wait-VMReady.ps1: remove unused $elapsed; simplify try/catch around
  native command (exit codes don't throw)
- Install-Runner.ps1: add deprecation notice pointing to Setup-Host.ps1

P2 operational:
- Add scripts/Cleanup-OrphanedBuildVMs.ps1 with -WhatIf support
- Get-BuildArtifacts.ps1 -IncludeLogs: add -Recurse (msbuild logs in subdir)
- Add gitea/workflows/lint.yml (PSScriptAnalyzer on .ps1 push/PR)

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

scripts/Wait-VMReady.ps1

@@ -75,15 +75,10 @@ while ((Get-Date) -lt $deadline) {
     $attempt++
 
     # ── Phase 1: VM must be running ─────────────────────────────────────
-    # vmrun has no getState; getGuestIPAddress fails with "not powered on"
-    # when the VM is off, and succeeds (exit 0) when running.
-    try {
-        & $VmrunPath getGuestIPAddress $VMPath 2>&1 | Out-Null
-        $isRunning = ($LASTEXITCODE -eq 0)
-    }
-    catch {
-        $isRunning = $false
-    }
+    # vmrun has no getState; getGuestIPAddress exits non-zero when the VM
+    # is not powered on. Native commands don't throw — check exit code only.
+    & $VmrunPath getGuestIPAddress $VMPath 2>&1 | Out-Null
+    $isRunning = ($LASTEXITCODE -eq 0)
 
     if (-not $isRunning) {
         if ($phase -ne 'vmrun-state') {
@@ -116,7 +111,6 @@ while ((Get-Date) -lt $deadline) {
     try {
         Test-WSMan -ComputerName $IPAddress -ErrorAction Stop | Out-Null
         # Success — VM is ready
-        $elapsed = ($deadline - (Get-Date)).Negate().TotalSeconds + $TimeoutSeconds
         Write-Host "[Wait-VMReady] VM ready after ~$([int]($attempt * $PollIntervalSeconds))s (attempt $attempt)."
         return
     }