feat: Extract react-ui package from assistant-ui monorepo

This repository contains the react-ui package extracted from the main
assistant-ui monorepo at commit 30c9f927 (the last commit before react-ui
was removed from the main repository).

The setup includes:
- react-ui package (v0.1.8) - Pre-styled React components
- tsbuildutils - Internal build utilities
- tailwindcss-transformer - Required dependency
- tsconfig - TypeScript configuration

Dependencies have been updated to use npm versions of @assistant-ui/react
and @assistant-ui/react-markdown instead of workspace versions.

🤖 Generated with Claude Code

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

Author: Yonom

.changeset/README.md

@@ -0,0 +1,8 @@
+# Changesets
+
+Hello and welcome! This folder has been automatically generated by `@changesets/cli`, a build tool that works
+with multi-package repos, or single-package repos to help you version and publish your code. You can
+find the full documentation for it [in our repository](https://github.com/changesets/changesets)
+
+We have a quick list of common questions to get you started engaging with this project in
+[our documentation](https://github.com/changesets/changesets/blob/main/docs/common-questions.md)

.changeset/config.json

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+{
+  "$schema": "https://unpkg.com/@changesets/config@3.0.1/schema.json",
+  "changelog": "@changesets/cli/changelog",
+  "commit": false,
+  "fixed": [],
+  "linked": [],
+  "access": "public",
+  "baseBranch": "main",
+  "privatePackages": { "version": false },
+  "updateInternalDependencies": "minor"
+}

.changeset/free-cows-appear.md

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+---
+"assistant-ui": patch
+---
+
+fix: init command does not work on empty folders

.changeset/public-clouds-train.md

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+---
+"assistant-stream": patch
+"@assistant-ui/react": patch
+---
+
+refactor: merge setResult and setArtifact to setResponse

.github/assets/assistant-ui-starter.gif

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+name: Changesets
+on:
+  push:
+    branches:
+      - main
+
+concurrency: ${{ github.workflow }}-${{ github.ref }}
+
+permissions:
+  id-token: write
+  contents: write
+  pull-requests: write
+
+env:
+  CI: true
+
+jobs:
+  version:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout code repository
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@v4
+
+      - name: Setup node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: "pnpm"
+
+      - name: Cache turbo build setup
+        uses: actions/cache@v4
+        with:
+          path: .turbo
+          key: ${{ runner.os }}-turbo-${{ github.sha }}
+          restore-keys: |
+            ${{ runner.os }}-turbo-
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+
+      - name: Create and publish versions
+        uses: changesets/action@v1
+        with:
+          commit: "chore: update versions"
+          title: "chore: update versions"
+          version: pnpm ci:version
+          publish: pnpm ci:publish
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          NPM_TOKEN: ${{ secrets.NPM_TOKEN }}