feat(activities): editingEvent in activities store

Carry the LNbits event being edited at store level so the
shell-mounted CreateEventDialog (activities-app/App.vue) can open in
edit mode from anywhere a user surfaces their own event — most
importantly the activity detail page, which is where they actually
land when fixing a posting.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/modules/activities/stores/activities.ts

@@ -1,6 +1,7 @@
 import { defineStore } from 'pinia'
 import { ref, computed } from 'vue'
 import type { Activity } from '../types/activity'
+import type { TicketedEvent } from '../types/ticket'
 
 /**
  * Pinia store for cached activities from Nostr relays.
@@ -14,6 +15,9 @@ export const useActivitiesStore = defineStore('activities', () => {
   /** Toggle by the standalone bottom-nav Create tab; mounted dialog lives
    * in activities-app/App.vue so it's available from every route. */
   const showCreateDialog = ref(false)
+  /** When set, the shell-mounted CreateEventDialog opens in edit mode
+   * for this LNbits event. Cleared when the dialog closes. */
+  const editingEvent = ref<TicketedEvent | null>(null)
 
   // Computed
   const activities = computed(() => Array.from(activitiesMap.value.values()))
@@ -88,6 +92,7 @@ export const useActivitiesStore = defineStore('activities', () => {
     isLoading,
     lastUpdated,
     showCreateDialog,
+    editingEvent,
 
     // Computed
     activities,