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

tests/e2e/extension.test.ts

@@ -0,0 +1,28 @@
+import { test, expect } from '@playwright/test';
+
+test('LexAI popup opens correctly', async ({ page }) => {
+  // Navigate to extension popup
+  await page.goto('chrome-extension://[EXTENSION_ID]/popup/index.html');
+
+  // Check LexAI branding is present
+  await expect(page.locator('text=LexAI')).toBeVisible();
+
+  // Check settings button is present
+  await expect(page.locator('button:has-text("Open Settings")')).toBeVisible();
+});
+
+test('Options page saves API key', async ({ page }) => {
+  await page.goto('chrome-extension://[EXTENSION_ID]/options/index.html');
+
+  // Fill in API key
+  await page.fill('input[type="password"]', 'sk-test-key');
+
+  // Select provider
+  await page.selectOption('select:first-of-type', 'openai');
+
+  // Save
+  await page.click('button:has-text("Save Settings")');
+
+  // Confirm saved
+  await expect(page.locator('text=Saved!')).toBeVisible();
+});