refactor(monitoring): consolidate workers and extract to scheduler process

Remove standalone lease-recovery, received-inspection, and result-recovery
workers from tenant-api (now handled by scheduler process). Add configurable
concurrency to ingest and projection-rebuild workers via MonitoringWorkers
runtime config. Extract shared runtime types for worker configuration.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/internal/tenant/app/monitoring_task_result_runtime.go

@@ -0,0 +1,22 @@
+package app
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+func decodeMonitoringTaskResultEnvelope(payload []byte) (*monitoringTaskResultEnvelope, error) {
+	if len(payload) == 0 {
+		return nil, fmt.Errorf("monitoring task result payload is empty")
+	}
+
+	var envelope monitoringTaskResultEnvelope
+	if err := json.Unmarshal(payload, &envelope); err != nil {
+		return nil, err
+	}
+	if envelope.TaskID <= 0 {
+		return nil, fmt.Errorf("monitoring task result payload missing task_id")
+	}
+
+	return &envelope, nil
+}