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/dto/today-summary-query.dto.ts

@@ -0,0 +1,20 @@
+import { ApiPropertyOptional } from '@nestjs/swagger';
+import { IsISO8601, IsOptional } from 'class-validator';
+
+export class TodaySummaryQueryDto {
+  @ApiPropertyOptional({
+    description: 'Start of the local day range (ISO 8601). Defaults to UTC midnight today.',
+    example: '2026-07-10T00:00:00.000Z',
+  })
+  @IsOptional()
+  @IsISO8601()
+  from?: string;
+
+  @ApiPropertyOptional({
+    description: 'End of the local day range (ISO 8601, exclusive). Defaults to next UTC midnight.',
+    example: '2026-07-11T00:00:00.000Z',
+  })
+  @IsOptional()
+  @IsISO8601()
+  to?: string;
+}