Fix audit findings: budget editing, dead code, logging, multi-currency

- Add budget editing: updateBudget() API, edit button on budget cards,
  BudgetFormModal adapted for create/update (category locked on edit)
- Remove permanently-broken POST /auth/totp/verify stub and its unused
  TOTPVerifyRequest schema
- Wire getHoldingTransactions() to AssetDetail page — transaction history
  table now shows above the candlestick chart, sorted newest-first
- Fix multi-currency net worth in account_service: account balances are
  now converted to base_currency via ExchangeRate table before summing
- Replace silent bare pass exception handlers with logger.warning() in
  transactions.py (OCR/AI pipeline) and price_feed_service.py (search)
  — ValueError in date/number regex parsing left silent (control flow)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/api/budgets.ts

@@ -60,6 +60,21 @@ export async function createBudget(data: BudgetCreate): Promise<Budget> {
   return r.data;
 }
 
+export interface BudgetUpdate {
+  name?: string;
+  amount?: number;
+  period?: "weekly" | "monthly" | "quarterly" | "yearly";
+  end_date?: string | null;
+  rollover?: boolean;
+  alert_threshold?: number;
+  is_active?: boolean;
+}
+
+export async function updateBudget(id: string, data: BudgetUpdate): Promise<Budget> {
+  const r = await api.put(`/budgets/${id}`, data);
+  return r.data;
+}
+
 export async function deleteBudget(id: string): Promise<void> {
   await api.delete(`/budgets/${id}`);
 }