feat: Expo mobile scaffold — Phase 2 complete (118-file structure)

Expo SDK 51 TypeScript scaffold with all architecture files.
Verified: tsc 0 errors, jest passes.

mobile/.eslintrc.js

@@ -0,0 +1,26 @@
+module.exports = {
+  root: true,
+  parser: '@typescript-eslint/parser',
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+    ecmaFeatures: {
+      jsx: true,
+    },
+  },
+  plugins: ['@typescript-eslint', 'react', 'react-hooks'],
+  extends: [
+    'eslint:recommended',
+    'plugin:react/recommended',
+    'plugin:react-hooks/recommended',
+    'plugin:@typescript-eslint/recommended',
+  ],
+  settings: {
+    react: {
+      version: 'detect',
+    },
+  },
+  rules: {
+    'react/react-in-jsx-scope': 'off',
+  },
+};