docs(expenses): add Tricount link to ledger and itinerary

expenses.md

@@ -1,5 +1,7 @@
 # Expense Ledger
 
+**Tricount:** <https://tricount.com/tOMVasoAGxPeQkMAJP> (opens in the app) — the live ledger; this file is a snapshot.
+
 Source: screenshot of the **LA Rookies** group in Tricount. The screenshot groups all entries under **“Today”** but does not show the calendar date or the split settings. The Tricount group's default currency is **USD**, so all ledger amounts below are recorded in USD.
 
 ## Summary