Implement tasks 25, 26 + completion visibility setting

Task 25: Multiple dashboards — dashboards table + migration, /d/[slug]
route, root redirect, dashboard tabs in nav with create/rename/delete/
set-default. Task 26: Editable dashboard — react-grid-layout drag/resize
editor, widget picker modal with per-widget configurator auto-generated
from default config, save/reset server actions with Zod validation.

Completion visibility: server-side per-user setting (hours) replaces
localStorage timer; queries filter completed items by updatedAt cutoff;
Settings page dropdown persists preference via server action.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/completion-delay-setting.tsx

@@ -1,25 +1,41 @@
 "use client";
 
-import { DELAY_OPTIONS, useCompletionDelay } from "@/hooks/use-completion-delay";
+import { useTransition } from "react";
+import { setCompletionVisibilityHours } from "@/app/settings/actions";
 
-export function CompletionDelaySetting() {
-  const { delay, setDelay } = useCompletionDelay();
+const OPTIONS = [
+  { label: "1 hour", value: 1 },
+  { label: "4 hours", value: 4 },
+  { label: "8 hours", value: 8 },
+  { label: "24 hours (default)", value: 24 },
+  { label: "48 hours", value: 48 },
+  { label: "7 days", value: 168 },
+  { label: "Never hide", value: 8760 },
+];
+
+export function CompletionDelaySetting({ initialHours }: { initialHours: number }) {
+  const [isPending, startTransition] = useTransition();
+
+  function handleChange(e: React.ChangeEvent<HTMLSelectElement>) {
+    const hours = Number(e.target.value);
+    startTransition(() => setCompletionVisibilityHours(hours));
+  }
 
   return (
     <div className="flex items-center justify-between gap-4">
       <div>
-        <p className="text-sm font-medium">Completion delay</p>
+        <p className="text-sm font-medium">Show completed items for</p>
         <p className="text-xs text-muted-foreground">
-          How long a checked-off item stays visible before disappearing from list cards and the
-          dashboard.
+          How long checked-off items remain visible on list cards and the dashboard.
         </p>
       </div>
       <select
-        value={delay}
-        onChange={(e) => setDelay(Number(e.target.value))}
-        className="rounded-md border border-input bg-background px-3 py-1.5 text-sm shadow-sm focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring"
+        defaultValue={initialHours}
+        onChange={handleChange}
+        disabled={isPending}
+        className="rounded-md border border-input bg-background px-3 py-1.5 text-sm shadow-sm focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring disabled:opacity-50"
       >
-        {DELAY_OPTIONS.map((opt) => (
+        {OPTIONS.map((opt) => (
           <option key={opt.value} value={opt.value}>
             {opt.label}
           </option>