Replace not-found exceptions in Arcadia find/show flows with typed outputs (Found*/NotFoundOutput) and map not-found results in presenters/responses while preserving HTTP 404 problem details.
Adjust architecture and unit tests to cover concrete output classes, and remove obsolete Arcadia not-found exception classes and their tests.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
docs(architecture): add request lifecycle documentation for Arcadia API
docs(architecture): add execution, transactions, and domain events documentation for Arcadia API
docs(architecture): add guide for creating a new use case in Arcadia API
docs(exceptions): summarize exception handling and HTTP status codes in Arcadia API
docs(tests): outline testing strategy and conventions for Arcadia API
style(openapi): correct description formatting in OpenAPI documentation
chore: remove outdated exceptions documentation
test: remove obsolete tests documentation
