fix(beszel): widget transparency, error handling, and cache invalidation

- Remove hardcoded background colors from Beszel grid/table widgets so
  the board's opacity slider controls the background via the parent
  card's --background-color CSS variable
- Grid: set bg="transparent" on inner Card components
- Table: override mantine-datatable default backgrounds to transparent
- Stats: make system selector toggle only visible on hover
- Stats: fix chart width/height(-1) warning by setting minHeight: 1
- All Beszel widgets: throw query errors to trigger the ErrorBoundary
  instead of silently rendering an empty/black UI
- Add retry: false to beszel-system-stats queries
- Add invalidateIntegrationCacheAsync() to clear all cached data and
  session stores for an integration when it is updated or deleted,
  preventing stale/errored data from persisting after config changes

packages/api/src/router/integration/integration-router.ts

@@ -27,6 +27,7 @@ import {
   integrationSecretKindObject,
 } from "@homarr/definitions";
 import { createIntegrationAsync } from "@homarr/integrations";
+import { invalidateIntegrationCacheAsync } from "@homarr/redis";
 import { byIdSchema } from "@homarr/validation/common";
 import {
   integrationCreateSchema,
@@ -469,6 +470,10 @@ export const integrationRouter = createTRPCRouter({
       kind: integration.kind,
       url: input.url,
     });
+
+    // Invalidate all cached data for this integration so that widgets pick up the
+    // new configuration immediately instead of serving stale (or errored) data.
+    await invalidateIntegrationCacheAsync(input.id);
   }),
   delete: protectedProcedure
     .meta({
@@ -490,6 +495,9 @@ export const integrationRouter = createTRPCRouter({
       }
 
       await ctx.db.delete(integrations).where(eq(integrations.id, input.id));
+
+      // Clean up any cached data left behind by the deleted integration.
+      await invalidateIntegrationCacheAsync(input.id);
     }),
   getIntegrationPermissions: protectedProcedure.input(byIdSchema).query(async ({ input, ctx }) => {
     await throwIfActionForbiddenAsync(ctx, eq(integrations.id, input.id), "full");