Add Codex 26.527 offline installer

Install-Codex-26.527.ps1

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+$ErrorActionPreference = "Stop"
+
+function Write-Step([string]$Message) {
+    Write-Host ((Get-Date).ToString("yyyy-MM-dd HH:mm:ss K") + "  " + $Message)
+}
+
+$Root = Split-Path -Parent $MyInvocation.MyCommand.Path
+$ZipPath = Join-Path $Root "Codex-26.527.7698.0-windows-x64-msix.zip"
+$ExtractPath = Join-Path $Root "Codex-26.527.7698.0-windows-x64-msix"
+$MsixPath = Join-Path $ExtractPath "OpenAI.Codex_26.527.7698.0_x64__2p2nqsd0c76g0.Msix"
+$ExpectedHash = "eb038b71b9138d739e652d51adc15b3628cac34441727916b64e6e4699d259a4"
+
+Write-Step "Checking Codex offline package at $ZipPath"
+if (!(Test-Path $ZipPath)) {
+    throw "Missing package zip: $ZipPath"
+}
+
+if (Test-Path $ExtractPath) {
+    Write-Step "Removing previous extraction folder"
+    Remove-Item -Recurse -Force $ExtractPath
+}
+
+Write-Step "Extracting Codex package"
+Expand-Archive -Path $ZipPath -DestinationPath $ExtractPath -Force
+
+Write-Step "Verifying MSIX hash"
+$ActualHash = (Get-FileHash -Algorithm SHA256 $MsixPath).Hash.ToLowerInvariant()
+if ($ActualHash -ne $ExpectedHash) {
+    throw "Hash mismatch for $MsixPath. Expected $ExpectedHash but got $ActualHash"
+}
+
+Write-Step "Installing Codex 26.527.7698.0 from MSIX"
+Add-AppxPackage -Path $MsixPath
+
+Write-Step "Verifying installed Codex package"
+Get-AppxPackage OpenAI.Codex |
+    Select-Object Name, PackageFullName, Version, InstallLocation |
+    Format-List
+
+Write-Step "Codex installation command completed"

README.md

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-# installations
+# Installations
 
+Offline installation packages that need a reliable transport through Gitea.
+
+## Codex 26.527 Windows x64
+
+Package:
+
+```text
+Codex-26.527.7698.0-windows-x64-msix.zip
+```
+
+Expected MSIX SHA-256 after extracting the zip:
+
+```text
+eb038b71b9138d739e652d51adc15b3628cac34441727916b64e6e4699d259a4
+```
+
+Install from PowerShell:
+
+```powershell
+.\Install-Codex-26.527.ps1
+```

SHA256SUMS-windows.txt

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+eb038b71b9138d739e652d51adc15b3628cac34441727916b64e6e4699d259a4  OpenAI.Codex_26.527.7698.0_x64__2p2nqsd0c76g0.Msix