Clean up dotnet-msbuild: unify lock files, compact skill, add .gitattributes (#116)

* Clean up dotnet-msbuild: unify lock files, compact skill, add .gitattributes

- Add .gitattributes with * text=auto eol=lf for consistent line endings
- Unify compiled knowledge lock file names across copilot-extension and
  agentic-workflows (build-errors, performance, style-and-modernization)
- Deduplicate KnowledgeMap in build.ps1 into shared KnowledgeGroups
- Compact directory-build-organization skill (16K -> 8K chars) so it fits
  within compiled bundle limits; move detailed examples to references/
- Remove broken links to non-existent docs/copilot-extension-design.md
- Regenerate all lock files

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Add repo-level AGENTS.md with component build instructions

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Inline references/ content during knowledge compilation

Update Read-Skill in build.ps1 to resolve [text](references/*.md) links
and replace them with the referenced file content. This ensures compiled
lock files include the full reference material alongside the SKILL.md
content.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Update agentic workflows to leverage compiled knowledge

- build-failure-analysis: add binlog-mcp tool usage, bin/obj clash and
  generated file checks, common error categories
- build-perf-audit: add bottleneck classification, concrete optimization
  recommendations (MSBuild Server, ArtifactsPath, graph build), incremental
  build health check
- msbuild-pr-review: reference AP codes from anti-pattern catalog, add
  Central Package Management and Directory.Build centralization checks

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

* Change agentic workflow triggers to comment-based invocation

- build-failure-analysis: /analyze-build-failure
- build-perf-audit: /audit-build-perf
- msbuild-pr-review: /review-msbuild

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

.gitattributes

@@ -0,0 +1,2 @@
+# Normalize all text files to LF line endings
+* text=auto eol=lf