Initial commit: G3FO recurring investment schedule frontend

Co-authored-by: Cursor <cursoragent@cursor.com>

src/composables/useUrlPreferences.ts

@@ -0,0 +1,26 @@
+import { useRoute, useRouter } from 'vue-router'
+import type { AppPreferences } from '@/config/urlPreferences'
+import type { AppLocale } from '@/i18n/locale'
+import { useAppStore } from '@/stores/app'
+import type { AppTheme } from '@/theme/types'
+
+export function useUrlPreferences() {
+  const route = useRoute()
+  const router = useRouter()
+  const appStore = useAppStore()
+
+  function replacePreferences(partial: Partial<AppPreferences>) {
+    const query = appStore.buildQueryForPreferences(partial, route.query)
+    router.replace({ path: route.path, hash: route.hash, query })
+  }
+
+  function setLocale(next: AppLocale) {
+    replacePreferences({ locale: next })
+  }
+
+  function setTheme(next: AppTheme) {
+    replacePreferences({ theme: next })
+  }
+
+  return { setLocale, setTheme }
+}