chore(configs): migrate oxlint→eslint presets, refactor tsconfig

- Replace @robonen/oxlint with @robonen/eslint (composable ESLint flat-config
  presets: base, typescript, vue, vitest, imports, node, stylistic).
- Plugins bundled as deps: typescript-eslint, eslint-plugin-vue,
  @vitest/eslint-plugin, eslint-plugin-import-x, eslint-plugin-n,
  eslint-plugin-unicorn, @stylistic/eslint-plugin.
- @robonen/tsconfig: add base/dom/node/vue configs for composite project refs.

configs/eslint/rules/imports.md

@@ -0,0 +1,27 @@
+# imports preset
+
+## Purpose
+
+Чистые границы модулей и предсказуемые импорты (через `eslint-plugin-import-x`).
+
+## Key Rules
+
+- `import-x/no-duplicates`.
+- `import-x/no-self-import`.
+- `import-x/no-cycle` (warn).
+- `import-x/no-mutable-exports`.
+- `import-x/consistent-type-specifier-style`: `prefer-top-level`.
+
+## Examples
+
+```ts
+// ✅ Good
+import type { User } from './types';
+import { getUser } from './service';
+
+// ❌ Bad
+import { getUser } from './service';
+import { getUser as getUser2 } from './service';
+
+export let state = 0;
+```