chore: harden Windows TeX Live install and default to latest

Improve Windows container reliability by pinning TeX Live installer mirrors with fallback and setting safer Chocolatey CI defaults. Make TeX Live version configurable via build arg and default to latest while retaining override support.

book/docker/windows/Dockerfile

@@ -4,11 +4,13 @@
 # - Quarto 1.9.27 via Scoop
 # - Python 3.13.1 + requirements
 # - Ghostscript + Inkscape (Chocolatey)
-# - TeX Live 2025.20251008.0+ (pinned version fixes install-tl.zip issue) + packages from tl_packages
+# - TeX Live (latest by default; overridable via TEXLIVE_VERSION build arg) + packages from tl_packages
 # - R 4.5.2 + packages via install_packages.R
 # - Verifications: versions, kpsewhich font files, TikZ smoke test
 
 FROM mcr.microsoft.com/windows/server:ltsc2022
+ARG TEXLIVE_VERSION=latest
+ENV TEXLIVE_VERSION=${TEXLIVE_VERSION}
 
 # Use Windows PowerShell initially
 SHELL ["powershell.exe", "-NoLogo", "-ExecutionPolicy", "Bypass", "-Command"]
@@ -87,6 +89,10 @@ RUN Write-Host '=== STARTING CHOCOLATEY INSTALLATION ===' ; `
     Write-Host '📦 Chocolatey install script executed' ; `
     Write-Host 'Verifying Chocolatey installation...' ; `
     choco --version ; `
+    Write-Host '🔧 Configuring Chocolatey for CI stability...' ; `
+    choco config set --name commandExecutionTimeoutSeconds --value 14400 ; `
+    choco feature disable --name showDownloadProgress ; `
+    Write-Host '✅ Chocolatey timeout/progress settings applied' ; `
     Write-Host '✅ Chocolatey installation complete'
 
 # ------------------------------------------------------------
@@ -101,12 +107,30 @@ RUN Write-Host '✅ Dependency file copy complete'
 # ------------------------------------------------------------
 # PHASE 4: Install TeX Live FIRST (Most complex, fail fast)
 # ------------------------------------------------------------
-RUN Write-Host '=== STARTING TEX LIVE INSTALLATION (2025) ===' ; `
-    Write-Host '📦 Installing TeX Live via Chocolatey (pinned to 2025.20251008.0+)...' ; `
-    choco install texlive --version=2025.20251008.0 -y ; `
+RUN Write-Host '=== STARTING TEX LIVE INSTALLATION ===' ; `
+    Write-Host "📦 Installing TeX Live via Chocolatey (version: $env:TEXLIVE_VERSION)..." ; `
+    $texLiveVersion = $env:TEXLIVE_VERSION ; `
+    $primaryMirror = 'https://ctan.math.illinois.edu/systems/texlive/tlnet' ; `
+    $fallbackMirror = 'https://mirror.clarkson.edu/ctan/systems/texlive/tlnet' ; `
+    $primaryParams = "'/InstallerParameters:-repository=$primaryMirror'" ; `
+    $fallbackParams = "'/InstallerParameters:-repository=$fallbackMirror'" ; `
+    Write-Host "🌐 Primary TeX Live mirror: $primaryMirror" ; `
+    if ($texLiveVersion -eq 'latest') { `
+        choco install texlive -y --params $primaryParams ; `
+    } else { `
+        choco install texlive --version=$texLiveVersion -y --params $primaryParams ; `
+    } ; `
     if ($LASTEXITCODE -ne 0) { `
-        Write-Host '❌ TeX Live installation failed' ; `
-        exit 1 ; `
+        Write-Host "⚠️ TeX Live install failed with primary mirror, retrying with fallback: $fallbackMirror" ; `
+        if ($texLiveVersion -eq 'latest') { `
+            choco install texlive -y --params $fallbackParams ; `
+        } else { `
+            choco install texlive --version=$texLiveVersion -y --params $fallbackParams ; `
+        } ; `
+        if ($LASTEXITCODE -ne 0) { `
+            Write-Host '❌ TeX Live installation failed after mirror fallback' ; `
+            exit 1 ; `
+        } ; `
     } ; `
     Write-Host '✅ TeX Live installed via Chocolatey' ; `
     `
@@ -127,6 +151,19 @@ RUN Write-Host '=== STARTING TEX LIVE INSTALLATION (2025) ===' ; `
     Write-Host '🔧 Adding TeX Live to PATH...' ; `
     $env:PATH = "$texLiveBin;$env:PATH" ; `
     Write-Host "✅ PATH updated with: $texLiveBin" ; `
+    Write-Host '🔧 Pinning tlmgr repository to stable mirror...' ; `
+    & "$texLiveBin\tlmgr.bat" option repository $primaryMirror ; `
+    if ($LASTEXITCODE -eq 0) { `
+        Write-Host "✅ tlmgr repository set to: $primaryMirror" ; `
+    } else { `
+        Write-Host "⚠️ Failed to set primary tlmgr mirror; attempting fallback: $fallbackMirror" ; `
+        & "$texLiveBin\tlmgr.bat" option repository $fallbackMirror ; `
+        if ($LASTEXITCODE -eq 0) { `
+            Write-Host "✅ tlmgr repository set to fallback: $fallbackMirror" ; `
+        } else { `
+            Write-Host '⚠️ Could not pin tlmgr repository, continuing with TeX Live defaults' ; `
+        } ; `
+    } ; `
     `
     Write-Host '📋 Reading collections from tl_packages...' ; `
     if (Test-Path 'C:\temp\tl_packages') { `