fix: add ESLint config for .mjs test files and fix rettime.cjs lint

- Add ESLint flat config blocks for *.mjs files (sourceType: module,
  node globals) and *.test.mjs / test/mock-server.mjs (jest plugin +
  globals), matching the existing *.test.js pattern
- Fix rettime.cjs empty catch: `catch (_) {}` → `catch { /* ignore */ }`
  to resolve no-unused-vars and no-empty ESLint errors

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sirugh

eslint.config.mjs

@@ -30,5 +30,32 @@ export default [
             'jest/valid-expect': 'error',
         },
     },
+    {
+        files: ['**/*.mjs'],
+        languageOptions: {
+            sourceType: 'module',
+            globals: {
+                ...globals.node,
+            },
+        },
+    },
+    {
+        files: ['**/*.test.mjs', 'test/mock-server.mjs'],
+        plugins: { jest: pluginJest },
+        languageOptions: {
+            sourceType: 'module',
+            globals: {
+                ...pluginJest.environments.globals.globals,
+                ...globals.node,
+            },
+        },
+        rules: {
+            'jest/no-disabled-tests': 'warn',
+            'jest/no-focused-tests': 'error',
+            'jest/no-identical-title': 'error',
+            'jest/prefer-to-have-length': 'warn',
+            'jest/valid-expect': 'error',
+        },
+    },
     pluginJs.configs.recommended,
 ];

test/__mocks__/rettime.cjs

@@ -37,7 +37,7 @@ class Emitter {
     const direct = this._listeners.get(name) || [];
     const wildcard = this._listeners.get('*') || [];
     for (const fn of [...direct, ...wildcard]) {
-      try { fn(event); } catch (_) {}
+      try { fn(event); } catch { /* ignore */ }
     }
     return this;
   }