Fix security vulnerabilities, resolve deprecation warnings, and upgrade to ESLint v10

.prettierignore

@@ -2,3 +2,6 @@ coverage
 node_modules
 
 lib
+# Auto-generated conversation history from the SpecStory VS Code extension.
+# Prettier 3 enforces stricter formatting on .md/.json that these files don't conform to.
+.specstory

eslint.config.mjs

@@ -0,0 +1,82 @@
+import tseslint from '@typescript-eslint/eslint-plugin';
+import tsparser from '@typescript-eslint/parser';
+import importPlugin from 'eslint-plugin-import-x';
+import eslintConfigPrettier from 'eslint-config-prettier';
+
+export default [
+  {
+    ignores: [
+      'out/**',
+      'dist/**',
+      '**/*.d.ts',
+      'coverage/**',
+      'node_modules/**',
+    ],
+  },
+  {
+    files: ['**/*.ts', '**/*.tsx', '**/*.js', '**/*.jsx'],
+    languageOptions: {
+      parser: tsparser,
+      parserOptions: {
+        project: './tsconfig.eslint.json',
+        sourceType: 'module',
+      },
+      ecmaVersion: 2020,
+      sourceType: 'module',
+      globals: {
+        console: 'readonly',
+        process: 'readonly',
+        __dirname: 'readonly',
+        __filename: 'readonly',
+        module: 'readonly',
+        require: 'readonly',
+        exports: 'readonly',
+        Buffer: 'readonly',
+      },
+    },
+    plugins: {
+      '@typescript-eslint': tseslint,
+      import: importPlugin,
+    },
+    rules: {
+      '@typescript-eslint/adjacent-overload-signatures': 'error',
+      '@typescript-eslint/no-empty-function': 'error',
+      '@typescript-eslint/no-empty-interface': 'warn',
+      '@typescript-eslint/no-namespace': 'error',
+      '@typescript-eslint/prefer-for-of': 'warn',
+      '@typescript-eslint/triple-slash-reference': 'error',
+      '@typescript-eslint/unified-signatures': 'warn',
+      'no-param-reassign': 'error',
+      'import/no-unassigned-import': 'warn',
+      'comma-dangle': ['error', 'only-multiline'],
+      'constructor-super': 'error',
+      eqeqeq: ['warn', 'always'],
+      'no-cond-assign': 'error',
+      'no-duplicate-case': 'error',
+      'no-duplicate-imports': 'error',
+      'no-empty': [
+        'error',
+        {
+          allowEmptyCatch: true,
+        },
+      ],
+      'spaced-comment': 'error',
+      'no-invalid-this': 'error',
+      'no-new-wrappers': 'error',
+      'no-redeclare': 'error',
+      'no-sequences': 'error',
+      'no-shadow': [
+        'error',
+        {
+          hoist: 'all',
+        },
+      ],
+      'no-throw-literal': 'error',
+      'no-unsafe-finally': 'error',
+      'no-unused-labels': 'error',
+      'no-var': 'warn',
+      'prefer-const': 'warn',
+    },
+  },
+  eslintConfigPrettier,
+];