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/lib/db/schema/clients.ts

@@ -6,7 +6,6 @@ import {
   numeric,
   jsonb,
   index,
-  uniqueIndex,
   primaryKey,
 } from 'drizzle-orm/pg-core';
 import { sql } from 'drizzle-orm';