feat: BuildKit client + integration test suite (651 tests)

BuildKitClient CLI wrapper for buildctl.
Docker compose stack (9 services) for integration testing.
Comprehensive test suite: wiremock tests for Matrix/La Suite/S3/client,
integration tests for Kratos/Hydra/Gitea/OpenSearch/Prometheus/Loki/
Grafana/LiveKit.

Bump: sunbeam-sdk v0.12.0

sunbeam-sdk/tests/config/prometheus.yml

@@ -0,0 +1,8 @@
+global:
+  scrape_interval: 5s
+  evaluation_interval: 5s
+
+scrape_configs:
+  - job_name: prometheus
+    static_configs:
+      - targets: ['localhost:9090']