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/app/api/v1/document-templates/merge-fields/route.ts

@@ -5,7 +5,7 @@ import { errorResponse } from '@/lib/errors';
 import { getMergeFields } from '@/lib/services/document-templates';
 
 export const GET = withAuth(
-  withPermission('documents', 'view', async (req, ctx) => {
+  withPermission('documents', 'view', async (_req, _ctx) => {
     try {
       const mergeFields = getMergeFields();
       return NextResponse.json({ data: mergeFields });

src/app/api/v1/expenses/export/csv/route.ts

@@ -1,7 +1,6 @@
 import { NextResponse } from 'next/server';
 
 import { withAuth, withPermission } from '@/lib/api/helpers';
-import { parseBody } from '@/lib/api/route-helpers';
 import { errorResponse } from '@/lib/errors';
 import { exportCsv } from '@/lib/services/expense-export';
 import { listExpensesSchema } from '@/lib/validators/expenses';

src/app/api/webhooks/documenso/route.ts

@@ -2,7 +2,6 @@ import { NextRequest, NextResponse } from 'next/server';
 import { createHash } from 'crypto';
 
 import { db } from '@/lib/db';
-import { documentEvents } from '@/lib/db/schema/documents';
 import { verifyDocumensoSignature } from '@/lib/services/documenso-webhook';
 import {
   handleRecipientSigned,