* Move Purview integration logic into middleware
* Improve error handling and user id management
* Rename purview package
* Handle 402s more explicitly; add Middleware generation methods; don't ignore exceptions
* Use DI container; pass scope id to PC
* Add protection scope caching
* Wrap more exceptions in PurviewClient
* Remove block check dedup; add tests
* Refactor PurviewWrapper intialization; Add unit tests
* Use different .Use method and add IDisposable stub
* Add background job processing for Purview
* Misc comment cleanup
* Apply copilot comments
* Fix formatting
* Formatting other files to fix pipeline
* Small updates to settings and exceptions
* Add README
* Move Purview sample
* Address review comments and update XML comments
* Newline after namespace
* Move public Purview classes to single namespace; Clean up csproj and slnx
* Commit the renames
* Remove unused openAI dependency
---------
Co-authored-by: Dmytro Struk <13853051+dmytrostruk@users.noreply.github.com>