feat(P0-001): scaffold monorepo structure

pnpm workspaces, Turborepo, TypeScript strict, ESLint flat config,
Prettier, Vitest, husky + lint-staged. Placeholder packages for all
16 packages + 2 apps + 2 plugins.

Closes #1

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

eslint.config.mjs

@@ -0,0 +1,26 @@
+import tseslint from 'typescript-eslint';
+import tsPlugin from '@typescript-eslint/eslint-plugin';
+import tsParser from '@typescript-eslint/parser';
+
+export default tseslint.config(
+  {
+    ignores: ['**/dist/**', '**/node_modules/**', '**/.next/**', '**/coverage/**'],
+  },
+  {
+    files: ['**/*.{ts,tsx}'],
+    plugins: {
+      '@typescript-eslint': tsPlugin,
+    },
+    languageOptions: {
+      parser: tsParser,
+      parserOptions: {
+        projectService: true,
+      },
+    },
+    rules: {
+      '@typescript-eslint/no-unused-vars': ['error', { argsIgnorePattern: '^_' }],
+      '@typescript-eslint/no-explicit-any': 'warn',
+      '@typescript-eslint/consistent-type-imports': 'error',
+    },
+  },
+);