Replace eslint-plugin-import with eslint-plugin-import-x

Switched from eslint-plugin-import to eslint-plugin-import-x to resolve
ESLint 10 peer dependency warning.

eslint-plugin-import-x is a maintained fork of eslint-plugin-import with
full ESLint 10 support and is a drop-in replacement.

Changes:
- Replaced eslint-plugin-import@2.32.0 with eslint-plugin-import-x@4.16.2
- Updated import in eslint.config.mjs
- All existing rules continue to work identically

Result:
- No peer dependency warnings
- All linting passing
- All tests passing
- Production build working
- 0 vulnerabilities

Author: dduugg

eslint.config.mjs

@@ -1,6 +1,6 @@
 import tseslint from '@typescript-eslint/eslint-plugin';
 import tsparser from '@typescript-eslint/parser';
-import importPlugin from 'eslint-plugin-import';
+import importPlugin from 'eslint-plugin-import-x';
 import eslintConfigPrettier from 'eslint-config-prettier';
 
 export default [