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>

frontend/src/types/today.ts

@@ -0,0 +1,32 @@
+export type TodayWidgetKey =
+  | 'appointmentsToday'
+  | 'patientsToday'
+  | 'treatmentsToday'
+  | 'draftTreatments'
+  | 'labCasesPendingSend'
+  | 'casesReceivedToday'
+  | 'tasksInProgress'
+  | 'importantTasks'
+  | 'pendingConnections'
+  | 'seats'
+  | 'pendingStaffInvites';
+
+export type TodaySummaryWidgets = Partial<
+  Record<
+    TodayWidgetKey,
+    | { count: number }
+    | { used: number; limit: number | null; unlimited: boolean }
+  >
+>;
+
+export interface TodaySummaryData {
+  generatedAt: string;
+  orgType: 'CLINIC' | 'LAB';
+  range: { from: string; to: string };
+  widgets: TodaySummaryWidgets;
+}
+
+export interface TodaySummaryResponse {
+  success: boolean;
+  data: TodaySummaryData;
+}