feat: portal cross-event my-shifts endpoint and dashboard page

GET /portal/my-shifts aggregates shift assignments across all events
the logged-in user is linked to via Person records. Groups by event
then date, showing only active assignments (approved/pending_approval)
for approved/pending persons.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

apps/portal/src/composables/api/usePortalShifts.ts

@@ -1,12 +1,25 @@
 import { useQuery, useMutation, useQueryClient } from '@tanstack/vue-query'
 import type { Ref } from 'vue'
 import { apiClient } from '@/lib/axios'
-import type { AvailableShiftsDay, MyShiftsResponse } from '@/types/portal-shift'
+import type { AllMyShiftsEventGroup, AvailableShiftsDay, MyShiftsResponse } from '@/types/portal-shift'
 
 interface ApiResponse<T> {
   data: T
 }
 
+export function useAllMyShifts() {
+  return useQuery({
+    queryKey: ['portal-all-my-shifts'],
+    queryFn: async () => {
+      const { data } = await apiClient.get<ApiResponse<AllMyShiftsEventGroup[]>>(
+        '/portal/my-shifts',
+      )
+
+      return data.data
+    },
+  })
+}
+
 export function useAvailableShifts(eventId: Ref<string | null>) {
   return useQuery({
     queryKey: ['available-shifts', eventId],