chore: initialize repository with project docs and tooling

- Add persistent docs: PRD, functional design, architecture, repository structure, development guidelines, milestones

- Add brainstorming notes (docs/ideas/)

- Configure tooling: package.json, tsconfig, eslint, prettier, vitest

- Add opencode configuration (commands, skills, agents)

- Add .gitignore for node_modules, .env, data/, backups/, build outputs

eslint.config.js

@@ -0,0 +1,23 @@
+import eslint from '@eslint/js';
+import tseslint from 'typescript-eslint';
+import prettierConfig from 'eslint-config-prettier';
+
+export default tseslint.config(
+  eslint.configs.recommended,
+  ...tseslint.configs.recommended,
+  prettierConfig,
+  {
+    rules: {
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        { argsIgnorePattern: '^_' },
+      ],
+      '@typescript-eslint/explicit-function-return-type': 'off',
+      '@typescript-eslint/explicit-module-boundary-types': 'off',
+      '@typescript-eslint/no-explicit-any': 'warn',
+    },
+  },
+  {
+    ignores: ['node_modules/**', 'dist/**', '.steering/**'],
+  }
+);