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/cmd/worker-generate/main.go

@@ -107,7 +107,7 @@ func main() {
 		kolWorker,
 		app.Logger,
 		app.Config().Generation,
-	).WithConfigProvider(app.ConfigStore).Start(ctx)
+	).WithCache(app.Cache).WithConfigProvider(app.ConfigStore).Start(ctx)
 
 	generateworker.NewTemplateAssistWorker(
 		app.RabbitMQ,