Initial scaffold with per-nameserver DNS monitoring model

Full project structure following upaas conventions: uber/fx DI, go-chi
routing, slog logging, Viper config. State persisted as JSON file with
per-nameserver record tracking for inconsistency detection. Stub
implementations for resolver, portcheck, tlscheck, and watcher.

internal/handlers/status.go

@@ -0,0 +1,23 @@
+package handlers
+
+import (
+	"net/http"
+)
+
+// HandleStatus returns the monitoring status handler.
+func (h *Handlers) HandleStatus() http.HandlerFunc {
+	type response struct {
+		Status string `json:"status"`
+	}
+
+	return func(
+		writer http.ResponseWriter,
+		request *http.Request,
+	) {
+		h.respondJSON(
+			writer, request,
+			&response{Status: "ok"},
+			http.StatusOK,
+		)
+	}
+}