feat: add dashboards — tables, CRUD API, widget data endpoint

- New dashboards table (name, description, layout, is_default)
- New dashboard_widgets table (view_id, title, widget_type, position, config)
- GET/POST/PATCH/DELETE /dashboards
- GET/POST/PATCH/DELETE /dashboards/:id/widgets
- GET /dashboards/:id/widgets/:id/data — runs saved view filters,
  returns pre-aggregated data for count/ticket_list/status_chart/grouped_counts
- is_default uniqueness enforced on PATCH

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/index.ts

@@ -13,6 +13,7 @@ import { createLifecyclesRouter } from './routes/lifecycles.ts';
 import { createUsersRouter } from './routes/users.ts';
 import { createTemplatesRouter } from './routes/templates.ts';
 import { createViewsRouter } from './routes/views.ts';
+import { createDashboardsRouter } from './routes/dashboards.ts';
 
 let db: Db | null = null;
 
@@ -37,6 +38,7 @@ app.route('/lifecycles', createLifecyclesRouter(getDb()));
 app.route('/users', createUsersRouter(getDb()));
 app.route('/templates', createTemplatesRouter(getDb()));
 app.route('/views', createViewsRouter(getDb()));
+app.route('/dashboards', createDashboardsRouter(getDb()));
 
 export default app;
 export { app };