Widen loadEnv schema type and allow rest-sibling destructuring in lint

loadEnv's ZodSchema<T> parameter required schema input === output,
which breaks any schema using .transform() (e.g. AppConfigSchema's
boolean coercion). Widen to ZodType<T, ZodTypeDef, unknown>, matching
existing runtime behavior. Also allow ignoreRestSiblings in the
no-unused-vars rule so 'const { X, ...rest } = obj' omission tests
don't trip the linter.

.eslintrc.cjs

@@ -7,6 +7,9 @@ module.exports = {
   parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
   ignorePatterns: ['dist', 'node_modules'],
   rules: {
-    '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
+    '@typescript-eslint/no-unused-vars': [
+      'error',
+      { argsIgnorePattern: '^_', ignoreRestSiblings: true },
+    ],
   },
 };