Install the SDK global.json pins before building.

The rebase onto upstream brought upstream's global.json, which pins SDK
10.0.400 with rollForward latestMajor. That version was released on
2026-08-11 and the hosted windows-latest image still tops out at 10.0.302,
and rollForward only rolls forward, so SDK resolution failed before the
build started - build 1.0.22 reported exit code 2147516571 and
"the following projects : [ '' ]" because dotnet never loaded a project.

Installing the pinned SDK in the pipeline keeps global.json byte identical
to upstream, so the merge surface stays at zero. azure-pipelines.yml is
ours alone, so changes here cost nothing when merging from VahidN.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: hgj52

azure-pipelines.yml

@@ -14,6 +14,15 @@ variables:
     minor: 0
 name: $(major).$(minor).$(Rev:r)
 steps:
+# The project targets net10.0 and global.json pins the SDK exactly, matching upstream.
+# Hosted images lag SDK releases by weeks, so install the pinned version rather than
+# relaxing global.json - that keeps the source identical to VahidN/iTextSharp.LGPLv2.Core
+# and leaves the merge surface at zero.
+- task: UseDotNet@2
+  displayName: Install the SDK global.json asks for
+  inputs:
+    packageType: 'sdk'
+    useGlobalJson: true
 - task: DotNetCoreCLI@2
   displayName: Build
   inputs: