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/auth/index.ts

@@ -2,7 +2,6 @@ import { betterAuth } from 'better-auth';
 import { drizzleAdapter } from 'better-auth/adapters/drizzle';
 
 import { db } from '@/lib/db';
-import { logger } from '@/lib/logger';
 
 /**
  * Better Auth server configuration.