Fix all ESLint errors: remove unused imports, replace any types

- Remove ~60 unused imports and variables across 88 files
- Replace ~80 `any` type annotations with proper types (unknown,
  Record<string, unknown>, or specific types)
- Prefix unused callback args with underscore
- Fix unescaped JSX entities
- Lint now passes cleanly (0 errors, 2 intentional img warnings)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/expenses/expense-columns.tsx

@@ -31,12 +31,6 @@ export interface ExpenseRow {
   createdAt: string;
 }
 
-const PAYMENT_STATUS_VARIANTS: Record<string, string> = {
-  unpaid: 'destructive',
-  paid: 'default',
-  partial: 'secondary',
-};
-
 const PAYMENT_STATUS_COLORS: Record<string, string> = {
   unpaid: 'bg-red-100 text-red-700 border-red-200',
   paid: 'bg-green-100 text-green-700 border-green-200',