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/modules/_core/schema.ts

@@ -1,5 +1,6 @@
 import type { AdapterAccountType } from "@auth/core/adapters";
 import {
+  boolean,
   index,
   integer,
   jsonb,
@@ -24,7 +25,7 @@ export const users = pgTable("users", {
   image: text("image"),
   theme: text("theme").notNull().default("default"),
   themeMode: text("theme_mode").notNull().default("system"),
-  defaultDashboardLayout: jsonb("default_dashboard_layout"),
+  completionVisibilityHours: integer("completion_visibility_hours").notNull().default(24),
   createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
 });
 
@@ -129,6 +130,24 @@ export const shareLinks = pgTable(
   ],
 );
 
+export const dashboards = pgTable(
+  "dashboards",
+  {
+    id: uuid("id").primaryKey().defaultRandom(),
+    userId: uuid("user_id")
+      .notNull()
+      .references(() => users.id, { onDelete: "cascade" }),
+    name: text("name").notNull(),
+    slug: text("slug").notNull(),
+    isDefault: boolean("is_default").notNull().default(false),
+    position: integer("position").notNull().default(0),
+    layout: jsonb("layout").notNull().default({ version: 1, widgets: [] }),
+    createdAt: timestamp("created_at", { withTimezone: true }).notNull().defaultNow(),
+    updatedAt: timestamp("updated_at", { withTimezone: true }).notNull().defaultNow(),
+  },
+  (t) => [uniqueIndex("dashboards_user_slug_uq").on(t.userId, t.slug)],
+);
+
 export const reminders = pgTable(
   "reminders",
   {