Fix screenshot action using wrong Playwright MCP tool name

[gaojude]

The screenshot action in browser_eval was calling browser_screenshot but Playwright MCP renamed this tool to browser_take_screenshot in a recent version. This caused screenshot attempts to fail with Tool "browser_screenshot" not found.

The fix updates the tool name mapping in the screenshot case to use the correct browser_take_screenshot name that Playwright MCP expects.

Fixes #94

> take a screenshot of homepage

⏺ next-devtools - browser_eval (MCP)(action: "start")
  ⎿  {
       "success": true,
       "message": "Browser automation started (chrome, headless: true)",
     … +4 lines (ctrl+o to expand)

⏺ next-devtools - browser_eval (MCP)(action: "navigate", url: "http://localhost:3000")
  ⎿  {
       "success": true,
       "action": "navigate",
     … +18 lines (ctrl+o to expand)

⏺ next-devtools - browser_eval (MCP)(action: "screenshot", fullPage: true)
  ⎿  {
       "success": true,
       "action": "screenshot",
     … +121 lines (ctrl+o to expand)

⏺ Read(/var/folders/p3/5q9n2fpn4y16zkx41c7d3dl40000gn/T/playwright-mcp-output/1764037588
      401/page-2025-11-25T02-26-31-831Z.png)
  ⎿  Read image (5.9KB)

⏺ Screenshot taken. The homepage shows:
  - "hello world" text at the top
  - A Next.js Dev Tools button in the bottom left corner

  Screenshot saved to: /var/folders/p3/5q9n2fpn4y16zkx41c7d3dl40000gn/T/playwright-m
  cp-output/1764037588401/page-2025-11-25T02-26-31-831Z.png