🔧 chore: add root ESLint config and enable lint in pre-commit

- Add eslint.config.mjs at root with TypeScript/JS rules
- Configure lint-staged to run ESLint --fix on JS/TS files
- Add ESLint dependencies to root package.json
- Set "type": "module" in package.json to fix module warning
- Ignore projects with their own ESLint configs

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

eslint.config.mjs

@@ -0,0 +1,67 @@
+// @ts-check
+import eslint from '@eslint/js';
+import eslintPluginPrettierRecommended from 'eslint-plugin-prettier/recommended';
+import globals from 'globals';
+import tseslint from 'typescript-eslint';
+
+/**
+ * Root ESLint config for the monorepo.
+ * Individual projects can override with their own eslint.config.* files.
+ */
+export default tseslint.config(
+	// Global ignores
+	{
+		ignores: [
+			'**/node_modules/**',
+			'**/dist/**',
+			'**/build/**',
+			'**/.svelte-kit/**',
+			'**/.expo/**',
+			'**/.next/**',
+			'**/coverage/**',
+			'**/apps-archived/**',
+			// Ignore projects with their own ESLint configs
+			'apps/manadeck/apps/mobile/**',
+			'apps/picture/apps/mobile/**',
+			'apps/picture/apps/web/**',
+			'games/voxel-lava/apps/web/**',
+		],
+	},
+	// Base JavaScript rules
+	eslint.configs.recommended,
+	// TypeScript rules (without type-checking for speed)
+	...tseslint.configs.recommended,
+	// Prettier integration
+	eslintPluginPrettierRecommended,
+	// Global settings
+	{
+		languageOptions: {
+			globals: {
+				...globals.node,
+				...globals.browser,
+				...globals.es2022,
+			},
+			ecmaVersion: 2022,
+			sourceType: 'module',
+		},
+	},
+	// TypeScript-specific rules (relaxed for monorepo compatibility)
+	{
+		files: ['**/*.ts', '**/*.tsx', '**/*.mts', '**/*.cts'],
+		rules: {
+			'@typescript-eslint/no-explicit-any': 'off',
+			'@typescript-eslint/no-unused-vars': [
+				'warn',
+				{ argsIgnorePattern: '^_', varsIgnorePattern: '^_' },
+			],
+			'@typescript-eslint/no-require-imports': 'off',
+		},
+	},
+	// JavaScript-specific rules
+	{
+		files: ['**/*.js', '**/*.jsx', '**/*.mjs', '**/*.cjs'],
+		rules: {
+			'no-unused-vars': ['warn', { argsIgnorePattern: '^_', varsIgnorePattern: '^_' }],
+		},
+	}
+);