feat: Outbox Inspector Minimal API endpoints (MapOutboxInspector)

[samtrion]

User Story

As a developer or operator monitoring the Pulse Outbox in production, I want minimal API endpoints for inspecting outbox messages and dead-letters, so that I can diagnose stuck messages, trigger replays, and dismiss failures without direct database access.

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Requirements

• Create OutboxInspectorOptions: BasePath = "/pulse/outbox", RouteGroupName = "Pulse Outbox Inspector".
• Create OutboxInspectorEndpoints (static class):
  • GET {base}/stats → IOutboxManagement.GetStatisticsAsync()
  • GET {base}/messages?count=50&skip=0 → IOutboxManagement.GetPendingAsync(count, skip)
  • GET {base}/messages/{id} → single message or 404
  • POST {base}/messages/{id}/replay → IOutboxManagement.ReplayAsync(id)
  • GET {base}/dead-letters → dead-letter list
  • POST {base}/dead-letters/{id}/dismiss → IOutboxManagement.DismissAsync(id)
  • POST {base}/dead-letters/replay-all → replay all dead-letters
• Add MapOutboxInspector(this IEndpointRouteBuilder, Action? configure = null) returning IEndpointConventionBuilder.
• No built-in authorization — user applies .RequireAuthorization() on the returned builder.

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Acceptance Criteria

• All seven endpoints respond with correct status codes.
• MapOutboxInspector() returns IEndpointConventionBuilder for chaining.
• BasePath is configurable via OutboxInspectorOptions.
• Unit tests cover all endpoints with mocked IOutboxManagement.