fix: register activities module in main app

The activities module was only registered in the standalone Sortir app,
not the main app. When events module was removed, its registration was
deleted but activities was never added in its place.

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

src/app.ts

@@ -13,6 +13,7 @@ import appConfig from './app.config'
 import baseModule from './modules/base'
 import nostrFeedModule from './modules/nostr-feed'
 import chatModule from './modules/chat'
+import activitiesModule from './modules/activities'
 import marketModule from './modules/market'
 import walletModule from './modules/wallet'
 import expensesModule from './modules/expenses'
@@ -43,6 +44,7 @@ export async function createAppInstance() {
     ...baseModule.routes || [],
     ...nostrFeedModule.routes || [],
     ...chatModule.routes || [],
+    ...activitiesModule.routes || [],
     ...marketModule.routes || [],
     ...walletModule.routes || [],
     ...expensesModule.routes || [],
@@ -111,6 +113,13 @@ export async function createAppInstance() {
     )
   }
 
+  // Register activities module (events + ticketing)
+  if (appConfig.modules.activities?.enabled) {
+    moduleRegistrations.push(
+      pluginManager.register(activitiesModule, appConfig.modules.activities)
+    )
+  }
+
   // Register market module
   if (appConfig.modules.market.enabled) {
     moduleRegistrations.push(