fix: Resolve ESLint configuration and fix all linting errors

- Changed npm lint script from 'next lint' to direct ESLint invocation
- Added 'lint:fix' script for auto-fixing linting errors
- Fixed 25 ESLint errors across the codebase:
  - 8 auto-fixed with --fix flag
  - 17 manual fixes (empty function warnings, type definitions)

ESLint now properly validates TypeScript and React code without
Next.js config wrapper incompatibility.

Test Results:
- ✅ npm run lint - No errors
- ✅ npm test - All tests passing
- ✅ npm run build - Clean build

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

next.config.js

@@ -7,10 +7,10 @@ const nextConfig = {
     optimizePackageImports: ['@phosphor-icons/react'],
   },
   eslint: {
-    ignoreDuringBuilds: true,
+    dirs: ['src', 'app', 'pages'],
   },
   typescript: {
-    ignoreBuildErrors: true,
+    tsconfigPath: './tsconfig.json',
   },
 }