feat: initial LexAI Chrome extension scaffold

- WXT + React 18 + TypeScript setup
- Background service worker (LLM API proxy)
- Content script (floating toolbar + text selection)
- Options page (provider/model/API key config)
- Popup UI
- Gitea Actions workflows (CI, preview, release)
- Vitest unit tests + Playwright E2E setup
- Supports: OpenAI, Anthropic, Groq, OpenRouter

.gitea/workflows/preview.yml

@@ -0,0 +1,52 @@
+name: Preview — PR Build Check
+
+on:
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  preview-build:
+    name: PR Preview Build
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '22'
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci
+
+      - name: Type check
+        run: npm run typecheck
+
+      - name: Run unit tests
+        run: npm test
+
+      - name: Build extension
+        run: npm run build
+
+      - name: Package preview ZIP
+        run: npm run zip
+
+      - name: Upload PR artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: lexai-pr-${{ github.event.pull_request.number }}-preview
+          path: .output/lexai-*.zip
+          retention-days: 3
+
+      - name: Comment on PR
+        uses: actions/github-script@v7
+        with:
+          script: |
+            github.rest.issues.createComment({
+              issue_number: context.issue.number,
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              body: `## ⚡ LexAI Preview Build Ready\n\n✅ Tests passed\n✅ Build successful\n\n📦 Download the extension ZIP from the **Artifacts** section above to test this PR.\n\nCommit: \`${{ github.sha }}\``
+            })