fix(beszel): harden cache layer and prevent blank widgets (#6052)

* fix(beszel): harden cache layer and prevent blank widgets

- Add debug logging across Beszel integration, request handler, and tRPC
  router (auth, fetch, SSE, per-procedure entry/exit) gated behind
  LOG_LEVEL=debug
- cached-request-handler: retry with backoff, isValid predicate to skip
  caching invalid data, in-flight dedup (single-flight per channel) to
  avoid thundering herd after cache invalidation
- redis channel: set-then-publish so storage is always consistent even
  when pubsub publish fails
- Beszel handlers: opt into fallbackToStaleOnError and retry so brief
  upstream hiccups don't throw away good cached data
- beszel-system-stats: add refetchInterval matching each time period's
  cache TTL so historical charts refresh in the background
- tRPC router: switch Promise.all -> Promise.allSettled for getSystems
  and getAlerts; getSystemStats returns an error object instead of
  throwing. Each result carries an optional error field so one failed
  integration no longer nukes the whole widget
- Widgets: add explicit isPending loader, empty state for grid and
  stats, and a shared per-integration error indicator (tooltip with
  failed integration names). Alerts and table now only show their
  empty state after loading completes
- Translation: add empty.noSystems key to beszelSystemGrid and
  beszelSystemStats

Addresses #6030

* style: auto-fix lint and format

---------

Co-authored-by: ajnart <ajnart@users.noreply.github.com>

packages/request-handler/src/beszel.ts

@@ -1,5 +1,6 @@
 import dayjs from "dayjs";
 
+import { createLogger } from "@homarr/core/infrastructure/logs";
 import { createIntegrationAsync } from "@homarr/integrations";
 import type {
   BeszelAlert,
@@ -13,6 +14,8 @@ import type {
 
 import { createCachedIntegrationRequestHandler } from "./lib/cached-integration-request-handler";
 
+const logger = createLogger({ module: "beszelRequestHandler" });
+
 export type { BeszelSystemRow } from "@homarr/integrations/types";
 
 /**
@@ -56,6 +59,7 @@ export const beszelSystemsRequestHandler = createCachedIntegrationRequestHandler
   Record<string, never>
 >({
   async requestAsync(integration) {
+    const start = performance.now();
     const instance = await createIntegrationAsync(integration);
     const systems = await instance.getSystemsAsync();
     const enriched = await Promise.all(
@@ -64,9 +68,16 @@ export const beszelSystemsRequestHandler = createCachedIntegrationRequestHandler
         return mapToSystemRow(system, details);
       }),
     );
+    logger.debug("beszelSystems fetch completed", {
+      integrationId: integration.id,
+      durationMs: Math.round(performance.now() - start),
+      count: enriched.length,
+    });
     return enriched;
   },
   cacheDuration: dayjs.duration(5, "seconds"),
+  fallbackToStaleOnError: true,
+  retry: { attempts: 2, delayMs: 500 },
   queryKey: "beszelSystems",
 });
 
@@ -81,12 +92,21 @@ export const beszelAlertsRequestHandler = createCachedIntegrationRequestHandler<
   { includeHistory: boolean; maxHistoryItems: number }
 >({
   async requestAsync(integration, input) {
+    const start = performance.now();
     const instance = await createIntegrationAsync(integration);
     const alerts = await instance.getAlertsAsync();
     const history = input.includeHistory ? await instance.getAlertHistoryAsync(undefined, input.maxHistoryItems) : [];
+    logger.debug("beszelAlerts fetch completed", {
+      integrationId: integration.id,
+      durationMs: Math.round(performance.now() - start),
+      alertsCount: alerts.length,
+      historyCount: history.length,
+    });
     return { alerts, history };
   },
   cacheDuration: dayjs.duration(15, "seconds"),
+  fallbackToStaleOnError: true,
+  retry: { attempts: 2, delayMs: 500 },
   queryKey: "beszelAlerts",
 });
 
@@ -110,15 +130,26 @@ export const beszelStatsRequestHandler = createCachedIntegrationRequestHandler<
   { systemId: string; timePeriod: string; includeDocker: boolean }
 >({
   async requestAsync(integration, input) {
+    const start = performance.now();
     const config = timePeriodConfig[input.timePeriod] ?? { type: "1m", perPage: 60, cacheSeconds: 60 };
     const instance = await createIntegrationAsync(integration);
     const systemStats = await instance.getSystemStatsAsync(input.systemId, config.type, config.perPage);
     const containerStats = input.includeDocker
       ? await instance.getContainerStatsAsync(input.systemId, config.type, config.perPage).catch(() => [])
       : [];
+    logger.debug("beszelStats fetch completed", {
+      integrationId: integration.id,
+      systemId: input.systemId,
+      timePeriod: input.timePeriod,
+      durationMs: Math.round(performance.now() - start),
+      systemStatsCount: systemStats.length,
+      containerStatsCount: containerStats.length,
+    });
     return { systemStats, containerStats };
   },
   cacheDuration: dayjs.duration(60, "seconds"),
+  fallbackToStaleOnError: true,
+  retry: { attempts: 2, delayMs: 500 },
   queryKey: "beszelStats",
   cacheDurationForInput(input) {
     const config = timePeriodConfig[input.timePeriod];