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/services/dashboard.service.ts

@@ -1,4 +1,4 @@
-import { and, count, desc, eq, inArray, isNull, sql, sum } from 'drizzle-orm';
+import { and, count, desc, eq, isNull, sql } from 'drizzle-orm';
 
 import { db } from '@/lib/db';
 import { clients } from '@/lib/db/schema/clients';