Integrate BACKBEAT SDK and resolve KACHING license validation

Major integrations and fixes:
- Added BACKBEAT SDK integration for P2P operation timing
- Implemented beat-aware status tracking for distributed operations
- Added Docker secrets support for secure license management
- Resolved KACHING license validation via HTTPS/TLS
- Updated docker-compose configuration for clean stack deployment
- Disabled rollback policies to prevent deployment failures
- Added license credential storage (CHORUS-DEV-MULTI-001)

Technical improvements:
- BACKBEAT P2P operation tracking with phase management
- Enhanced configuration system with file-based secrets
- Improved error handling for license validation
- Clean separation of KACHING and CHORUS deployment stacks

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

vendor/github.com/huin/goupnp/httpu/multiclient.go

@@ -0,0 +1,132 @@
+package httpu
+
+import (
+	"net/http"
+	"time"
+
+	"golang.org/x/sync/errgroup"
+)
+
+// MultiClient dispatches requests out to all the delegated clients.
+type MultiClient struct {
+	// The HTTPU clients to delegate to.
+	delegates []ClientInterface
+}
+
+var _ ClientInterface = &MultiClient{}
+
+// NewMultiClient creates a new MultiClient that delegates to all the given
+// clients.
+func NewMultiClient(delegates []ClientInterface) *MultiClient {
+	return &MultiClient{
+		delegates: delegates,
+	}
+}
+
+// Do implements ClientInterface.Do.
+func (mc *MultiClient) Do(
+	req *http.Request,
+	timeout time.Duration,
+	numSends int,
+) ([]*http.Response, error) {
+	tasks := &errgroup.Group{}
+
+	results := make(chan []*http.Response)
+	tasks.Go(func() error {
+		defer close(results)
+		return mc.sendRequests(results, req, timeout, numSends)
+	})
+
+	var responses []*http.Response
+	tasks.Go(func() error {
+		for rs := range results {
+			responses = append(responses, rs...)
+		}
+		return nil
+	})
+
+	return responses, tasks.Wait()
+}
+
+func (mc *MultiClient) sendRequests(
+	results chan<- []*http.Response,
+	req *http.Request,
+	timeout time.Duration,
+	numSends int,
+) error {
+	tasks := &errgroup.Group{}
+	for _, d := range mc.delegates {
+		d := d // copy for closure
+		tasks.Go(func() error {
+			responses, err := d.Do(req, timeout, numSends)
+			if err != nil {
+				return err
+			}
+			results <- responses
+			return nil
+		})
+	}
+	return tasks.Wait()
+}
+
+// MultiClientCtx dispatches requests out to all the delegated clients.
+type MultiClientCtx struct {
+	// The HTTPU clients to delegate to.
+	delegates []ClientInterfaceCtx
+}
+
+var _ ClientInterfaceCtx = &MultiClientCtx{}
+
+// NewMultiClient creates a new MultiClient that delegates to all the given
+// clients.
+func NewMultiClientCtx(delegates []ClientInterfaceCtx) *MultiClientCtx {
+	return &MultiClientCtx{
+		delegates: delegates,
+	}
+}
+
+// DoWithContext implements ClientInterfaceCtx.DoWithContext.
+func (mc *MultiClientCtx) DoWithContext(
+	req *http.Request,
+	numSends int,
+) ([]*http.Response, error) {
+	tasks, ctx := errgroup.WithContext(req.Context())
+	req = req.WithContext(ctx) // so we cancel if the errgroup errors
+	results := make(chan []*http.Response)
+
+	// For each client, send the request to it and collect results.
+	tasks.Go(func() error {
+		defer close(results)
+		return mc.sendRequestsCtx(results, req, numSends)
+	})
+
+	var responses []*http.Response
+	tasks.Go(func() error {
+		for rs := range results {
+			responses = append(responses, rs...)
+		}
+		return nil
+	})
+
+	return responses, tasks.Wait()
+}
+
+func (mc *MultiClientCtx) sendRequestsCtx(
+	results chan<- []*http.Response,
+	req *http.Request,
+	numSends int,
+) error {
+	tasks := &errgroup.Group{}
+	for _, d := range mc.delegates {
+		d := d // copy for closure
+		tasks.Go(func() error {
+			responses, err := d.DoWithContext(req, numSends)
+			if err != nil {
+				return err
+			}
+			results <- responses
+			return nil
+		})
+	}
+	return tasks.Wait()
+}