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/ci.yml

@@ -0,0 +1,57 @@
+name: CI — Test & Build
+
+on:
+  push:
+    branches: [main, develop]
+  pull_request:
+    branches: [main]
+
+jobs:
+  test:
+    name: Unit Tests
+    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
+
+  build:
+    name: Build Extension
+    runs-on: ubuntu-latest
+    needs: test
+    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: Build extension
+        run: npm run build
+
+      - name: Upload build artifact
+        uses: actions/upload-artifact@v4
+        with:
+          name: lexai-chrome-mv3-${{ github.sha }}
+          path: .output/chrome-mv3/
+          retention-days: 7