Merge latest Library.Template

[Copilot]

• Inspect repository status, contribution instructions, and current CI run state
• Run the required ./tools/MergeFrom-Template.ps1 merge from Library.Template tip 7b5f5bfa226bc7c32aed79544eb54b2838668d4d
• Resolve merge conflicts per policy, including keeping current README.md and preserving repository-specific files
• Verify the resulting merge commit has 7b5f5bfa226bc7c32aed79544eb54b2838668d4d as the second parent / SourceCommit
• Run required validation: dotnet restore, dotnet build, and tools/dotnet-test-cloud.ps1
• Run secret scanning and parallel validation before finalizing
• Update PR title/body requirements and leave the branch ready for merge-commit auto-merge

Original prompt

Update this repo to the current Library.Template tip via a TRUE merge commit (not squash/rebase-only).

Critical target

Library.Template tip (must be the merge SourceCommit / second parent):
7b5f5bfa226bc7c32aed79544eb54b2838668d4d
(has docfx 2.80.1, ubuntu 26, MTP 2.4.1, etc.)

This repo is behind tip (docfx still 2.78.5 in .config/dotnet-tools.json). There is NO open auto/libtemplateUpdate PR — create a new PR with title exactly: Merge latest Library.Template

You MUST run ./tools/MergeFrom-Template.ps1 so the merge commit's SourceCommit/second parent is exactly 7b5f5bfa226bc7c32aed79544eb54b2838668d4d.

Follow the update-library-template skill

Instructions mirror https://github.com/AArnott/Library.Template/blob/main/.agents/skills/update-library-template/SKILL.md and template-release-notes.md:

1. From repo root, run ./tools/MergeFrom-Template.ps1 (creates a true git merge --no-ff from Library.Template).
2. Resolve merge conflicts per policy:
   • Always keep CURRENT version of README.md (discard incoming).
   • Refer to template-release-notes.md for special notes (incoming side).
   • When incoming changes a file deleted locally, typically re-delete; but apply test project template changes (e.g. test/Library.Tests/Library.Tests.csproj) to all real test projects, then re-delete the template file.
   • Never leave Library.slnx; migrate root .sln to .slnx with dotnet solution EXISTING.sln migrate if needed; update script/doc references.
   • Some repos intentionally reject template patterns (e.g. MTPv2); if unclear whether to catch up or keep current, leave clear notes rather than guessing wrongly.
3. Validate after conflict resolution:
   • dotnet restore succeeds
   • dotnet build succeeds
   • tools/dotnet-test-cloud.ps1 succeeds
     (If azure-pipelines/dotnet.yml or .github/workflows/build.yml use msbuild.exe instead of dotnet CLI, validate with that tool.)
4. You are not responsible for unrelated pre-existing failures; if validation fails for reasons unrelated to the merge, document that clearly.
5. Committing:
   • Preserve the merge commit (do not squash the template merge).
   • Conflict-resolution fixes ideally amended into the merge commit; novel fixes for SDK/dependency breaks go in SEPARATE commits after the merge.
   • Author commits as: git commit --author "🤖 Copilot <no-reply@github.com>"
   • Describe conflict resolutions in the commit message.

PR requirements

• Title must be exactly: Merge latest Library.Template
• Body should note this is a merge (not squash) and that SourceCommit is 7b5f5bfa226bc7c32aed79544eb54b2838668d4d.
• After done, leave the PR ready for MERGE-method auto-merge (not squash).