feat: phase 3 - ledger and asset management

Add group expense tracking (ledger) and public asset inventory (asset) features.
Ledger supports income/expense recording with monthly summary. Asset tracks
group equipment with free-form holder transfer. Both are independent pages
accessible from GroupView navigation.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/router/index.ts

@@ -33,6 +33,20 @@ const routes: RouteRecordRaw[] = [
         component: () => import('@/views/GroupView.vue'),
         props: true
       },
+      {
+        path: 'group/:groupId/ledger',
+        name: 'LedgerView',
+        component: () => import('@/views/LedgerView.vue'),
+        props: true,
+        meta: { requiresAuth: true }
+      },
+      {
+        path: 'group/:groupId/assets',
+        name: 'AssetView',
+        component: () => import('@/views/AssetView.vue'),
+        props: true,
+        meta: { requiresAuth: true }
+      },
       {
         path: 'games',
         name: 'GamesLibrary',