Background Services Authentication Flow

[ArturKarbone]

No description provided.

[Copilot]

Pull request overview

Adds a new Poc.BackgroundWorker sample demonstrating machine-to-machine authentication for background services using OAuth2 client-credentials (Keycloak) to call the existing Weather API through YARP.

Changes:

• Introduces a .NET worker service that acquires client-credentials tokens and periodically calls /weatherforecast via YARP.
• Adds token acquisition service code (plus an optional cached wrapper) and sample configuration.
• Adds documentation for background-service authentication and updates solution/launch configuration to include the new sample.

Reviewed changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
samples/Poc.BackgroundWorker/appsettings.json	Adds Keycloak/YARP/worker polling configuration for the new sample.
samples/Poc.BackgroundWorker/appsettings.Development.json	Development logging overrides for the new worker.
samples/Poc.BackgroundWorker/Workers/WeatherBackgroundService.cs	Implements periodic token acquisition + API call + logging for the worker.
samples/Poc.BackgroundWorker/Services/ClientCredentialsTokenService.cs	Implements client-credentials token acquisition against Keycloak token endpoint.
samples/Poc.BackgroundWorker/Services/CachedClientCredentialsTokenService.cs	Adds an in-memory caching wrapper for tokens (currently not wired up).
samples/Poc.BackgroundWorker/README.md	Usage/architecture/docs for running the background worker sample.
samples/Poc.BackgroundWorker/Program.cs	Registers OIDC options, HttpClient, token service, and hosted worker.
samples/Poc.BackgroundWorker/Poc.BackgroundWorker.csproj	New worker project file and package references.
samples/Poc.Api/Program.cs	Minor whitespace cleanup in OIDC options configuration.
docs/BACKGROUND-SERVICES-AUTHENTICATION.md	New guide explaining background-service authentication and token caching.
AppForeach.TokenHandler.slnLaunch	Updates launch profile to start API + internal API + YARP + background worker.
AppForeach.TokenHandler.sln	Adds new project and docs solution items.