feat: publish standalone worker

Separate worker packaging and service lifecycle from the control plane.

internal/sender/sender.go

@@ -0,0 +1,33 @@
+package sender
+
+import (
+	"net/http"
+	"time"
+)
+
+var httpClient *http.Client
+
+func init() {
+	httpClient = &http.Client{
+		Timeout: time.Second * 60,
+	}
+}
+
+// Init sender
+//
+// Deprecated: the legacy SMPP init that lived here is commented out. Phase 3
+// of docs/plans/worker-notifier-mvp.md retires the sender loop entirely.
+// This stub is preserved so any remaining callers do not fail to compile
+// during the rollout window.
+func Init() {
+	// if application.Env == "production" {
+	// InitSMPP()
+	// }
+}
+
+// Start sender
+//
+// Deprecated: the legacy sender loop is retired. The worker binary is the executor.
+func Start() {
+	// no-op
+}