feat(cache,worker): overhaul cache layer and add generation task lease recovery

- shared/cache: add Options/L1/async/metrics/prefix decorators, multi-key ops, Redis pool tuning, and JSON readthrough metrics
- worker-generate: claim tasks via DB lease + heartbeat, requeue stale queued tasks, expire dead leases with refund/cache invalidation
- tenant: version article cache keys so worker recovery invalidations propagate cleanly
- shared/config: expand Redis (pool/timeouts/TLS) and Generation (lease/recovery) configs with defaults

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

server/internal/tenant/app/monitoring_metrics_prometheus.go

@@ -9,10 +9,12 @@ import (
 	promcollectors "github.com/prometheus/client_golang/prometheus/collectors"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/prometheus/common/expfmt"
+
+	"github.com/geo-platform/tenant-api/internal/shared/cache"
 )
 
 func MonitoringSchedulerMetricsPrometheusHandler() http.Handler {
-	return monitoringPrometheusHandler(true, monitoringDailyTaskMetricsCollector{})
+	return monitoringPrometheusHandler(true, monitoringDailyTaskMetricsCollector{}, cache.MetricsCollector{})
 }
 
 func MonitoringDailyTaskMetricsPrometheus() string {