feat: publish standalone worker

Separate worker packaging and service lifecycle from the control plane.

internal/sender/context_test.go

@@ -0,0 +1,34 @@
+package sender
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestMattermostContextDeadlineInterruptsBlockingRequest(t *testing.T) {
+	started := make(chan struct{})
+	release := make(chan struct{})
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		close(started)
+		<-release
+	}))
+	defer server.Close()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Millisecond)
+	defer cancel()
+	_, err := SendMattermostWithCredentialContext(ctx, server.URL, "maintenance_start", "subject", "body", nil)
+	select {
+	case <-started:
+	case <-time.After(time.Second):
+		t.Fatal("request did not reach blocking server")
+	}
+	close(release)
+	require.Error(t, err)
+	require.True(t, errors.Is(err, context.DeadlineExceeded))
+}