Epic: Axlis sample showcase

[marioarce]

Track the initial build of the Axlis Clean Architecture sample: a showcase WebApi used to test Axlis 0.1.0-preview against a real Sitecore instance before release.

Phases:

• Repo setup #2 Repo setup: import history, upstream remote, branch workflow
• Axlis wiring #3 Axlis wiring: DI registration, configuration, user-secrets
• Sample template POCOs #4 Sample Sitecore template POCOs
• CQRS showcase endpoint #5 CQRS Sitecore showcase endpoint (Pivots)
• Sample docs and README #6 Sample docs and README

Notes:

• Axlis is referenced via ProjectReference during testing (dev-only, marked with // fixme); switch to NuGet before any release.
• Environment-specific values (endpoint, API key, pivot paths, template GUIDs) are not committed; secrets live in user-secrets.