Add Today dashboard foundation with permission-aware KPI summary API.

Replace hardcoded Today cards with a backend summary endpoint and composable frontend widgets filtered by org type and tab permissions.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/src/modules/today/today.module.ts

@@ -0,0 +1,9 @@
+import { Module } from '@nestjs/common';
+import { TodayController } from './today.controller';
+import { TodayService } from './today.service';
+
+@Module({
+  controllers: [TodayController],
+  providers: [TodayService],
+})
+export class TodayModule {}