Add bulk actions, multi-currency, expenses, templates, and reports

Schema (migration 0001):
- clients: add currency column (default USD)
- invoices: add currency column (default USD)
- New expenses table: amount, currency, category, billable, reimbursable,
  client/invoice/business relations, notes
- New invoice_templates table: name, type (notes|terms), content, isDefault

API:
- invoices: add bulkUpdateStatus and bulkDelete procedures (ownership-safe)
- invoices: currency field threaded through create/update schemas
- clients: currency field added to create/update schemas
- New expenses router: full CRUD with authorization
- New invoiceTemplates router: full CRUD, isDefault management per type
- Root router: wire in expenses and invoiceTemplates

Currency (src/lib/currency.ts):
- Shared formatCurrency(amount, currency) utility replacing hardcoded USD
- SUPPORTED_CURRENCIES list (17 currencies)
- Invoice form: currency selector in Config card, auto-fills from client
- Client form: currency selector in Billing Information card

Bulk actions (invoices list):
- Checkbox column with select-all support
- Selection toolbar: Mark as Sent/Paid/Draft dropdown, Delete (N) button
- DataTable: new selectionActions prop renders toolbar when rows selected

Notes templates:
- Invoice form: Notes card with textarea in Details tab
- Template dropdown button appears when templates exist
- /dashboard/invoices/templates: full CRUD page for notes and terms templates

New pages:
- /dashboard/expenses: expense list with summary cards, add/edit dialog
- /dashboard/reports: KPI cards, 12-month revenue area chart, top clients
  bar chart, status breakdown, recent activity
- Navigation: Expenses and Reports added to Main section

https://claude.ai/code/session_012sqEgNQpx676isepeoX4Mi

src/lib/currency.ts

@@ -0,0 +1,30 @@
+export const SUPPORTED_CURRENCIES = [
+  { code: "USD", label: "USD – US Dollar" },
+  { code: "EUR", label: "EUR – Euro" },
+  { code: "GBP", label: "GBP – British Pound" },
+  { code: "CAD", label: "CAD – Canadian Dollar" },
+  { code: "AUD", label: "AUD – Australian Dollar" },
+  { code: "NZD", label: "NZD – New Zealand Dollar" },
+  { code: "CHF", label: "CHF – Swiss Franc" },
+  { code: "JPY", label: "JPY – Japanese Yen" },
+  { code: "SGD", label: "SGD – Singapore Dollar" },
+  { code: "HKD", label: "HKD – Hong Kong Dollar" },
+  { code: "SEK", label: "SEK – Swedish Krona" },
+  { code: "NOK", label: "NOK – Norwegian Krone" },
+  { code: "DKK", label: "DKK – Danish Krone" },
+  { code: "MXN", label: "MXN – Mexican Peso" },
+  { code: "BRL", label: "BRL – Brazilian Real" },
+  { code: "INR", label: "INR – Indian Rupee" },
+  { code: "ZAR", label: "ZAR – South African Rand" },
+] as const;
+
+export type CurrencyCode = (typeof SUPPORTED_CURRENCIES)[number]["code"];
+
+export function formatCurrency(amount: number, currency = "USD"): string {
+  return new Intl.NumberFormat("en-US", {
+    style: "currency",
+    currency,
+    minimumFractionDigits: 2,
+    maximumFractionDigits: 2,
+  }).format(amount);
+}