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>

package.json

@@ -30,6 +30,7 @@
     "@types/node": "^22.9.0",
     "@types/react": "^19.2.14",
     "@types/react-dom": "^19.2.3",
+    "@types/react-grid-layout": "^2.1.0",
     "drizzle-kit": "^0.31.10",
     "eslint": "^9.15.0",
     "eslint-config-next": "^16.2.4",
@@ -58,6 +59,7 @@
     "postgres": "^3.4.9",
     "react": "^19.2.5",
     "react-dom": "^19.2.5",
+    "react-grid-layout": "^2.2.3",
     "shadcn": "^4.7.0",
     "tailwind-merge": "^3.5.0",
     "tw-animate-css": "^1.4.0",