feat: publish standalone worker

Separate worker packaging and service lifecycle from the control plane.

internal/sender/get_content.go

@@ -0,0 +1,19 @@
+package sender
+
+import (
+	"bytes"
+	"time"
+
+	"rsgit.ru/rsmon/rsmon/app/models"
+	"rsgit.ru/rsmon/rsmon/internal/notifyrender"
+)
+
+// GetContent provides functionality.
+//
+// Deprecated: the worker-driven notifier producer now uses
+// internal/notifyrender directly. This thin wrapper is preserved so the
+// legacy RunMessage loop still compiles until it is removed in phase 3 of
+// docs/plans/worker-notifier-mvp.md.
+func GetContent(message *models.Message, tn time.Time) (bytes.Buffer, bytes.Buffer, bytes.Buffer, bytes.Buffer) {
+	return notifyrender.GetContent(message, tn)
+}