Internal Admin Dashboard Template for Lovable

# Context
Build an internal dashboard that answers what is happening right now, for a team operating a
product rather than browsing analytics. The reader is an operator on a shift, so the page
must be legible in five seconds and must never show a number without a time window.

## Core Features (Priority Order)
1. Role-gated access: only users with the admin role may open the dashboard at all
2. Four headline metrics with an explicit window on each, such as last 24 hours
3. One time-series chart with a selectable range, defaulting to 7 days
4. A recent-events table, newest first, paginated
5. An empty state that distinguishes "no data yet" from "query failed"

## Visual Style
- Information density over whitespace, but one clear hierarchy: metrics, chart, table
- shadcn/ui: Card for metric tiles, Table for events, Tabs or Select for the range picker,
  Skeleton for loading, Badge for event severity
- Numbers right-aligned and tabular, so columns scan vertically

## Technical Requirements
- Breakpoints sm 640px, md 768px, lg 1024px; the table scrolls inside its own container
  rather than making the page scroll sideways
- Every metric states its window in the tile, not in a tooltip
- Loading skeletons sized to the final content, so nothing jumps
- Distinguish zero from unknown: render a dash for a failed query, never 0
- Dark mode via Tailwind's dark: prefix

## Implementation Strategy
1. The admin role check and the route guard, before any query
2. One metric tile end to end against the schema in schema.sql
3. The remaining tiles, then the events table
4. The chart last, because it depends on the aggregate function being settled

## Safe-Guard Instructions
- A dashboard is not an implementation of access control. Enforce the admin check in the
  data layer as well as the UI: the policies in schema.sql do this.
- Never expose raw event payloads to a non-admin.
- Do not add a policy that lets a user read all events "for testing".
- Aggregate reads must respect the same policies as row reads.

## Growth Features (Required for Distribution)
- **Product-led Growth:** expose a narrow, read-only version of one metric to ordinary users
  in their own account view, so the value of the data is visible without granting admin.

-- Internal dashboard schema for Lovable + Supabase
-- Reviewed row-level security. Read the comments before running this.
--
-- The point of this file: role checks live in the database, not only in the UI. A generated
-- dashboard that hides a menu item is not access control.

create type public.app_role as enum ('admin', 'member');

create table public.user_roles (
  user_id uuid not null references auth.users (id) on delete cascade,
  role public.app_role not null default 'member',
  created_at timestamptz not null default now(),

-- Verification queries. Run these as an ordinary member first, then as an admin.
-- The member results are the ones that prove the policies work.

-- As a MEMBER (no admin role):

-- 1. Should return only your own events, never the whole table.
select id, name, user_id from public.events order by created_at desc limit 20;

-- 2. Should return only your own role row.
select * from public.user_roles;

-- 3. Should FAIL. There is no insert policy on user_roles, so nobody self-promotes.