fix(screenshot): error when webp dimensions exceed 16383px limit

[Mohan Ram (mohanram-dev)]

Fixes #42717

Description

WebP format uses 14 bits for pixel width and height (2^14 - 1 = 16,383 px maximum). When taking a screenshot with type: 'webp' where either width or height exceeds 16,383 pixels:

1. Chromium's Skia encoder cannot encode the image into WebP and returns empty image data ({ data: '' }).
2. Playwright previously converted this to a 0-byte Buffer (Buffer.from('', 'base64')) and silently returned it as a successful screenshot.
3. In @playwright/mcp, browser_take_screenshot wrote a 0-byte file to disk and returned an empty image without raising an error.

Changes

• In crPage.ts, compute renderScale (factoring in deviceScaleFactor when scale: 'device'). If format === 'webp' and either width or height exceeds 16,383 pixels, throw Cannot take screenshot larger than 16383 pixels on any dimension when using webp format.
• In crPage.ts and screenshotter.ts, guard against empty screenshot data by throwing Failed to take screenshot, received empty image data from browser if empty data is returned.
• In wkPage.ts and wvPage.ts, validate the 16,383 px limit for WebP format in validateScreenshotDimension.
• In @playwright/mcp's browser_take_screenshot tool, ensure empty image data throws an error rather than writing a 0-byte file.
• Added regression tests in tests/mcp/screenshot.spec.ts and tests/page/page-screenshot.spec.ts.

[Devin Rousso (dcrousso)]

this is really an upstream issue and should be fixed there instead (and also i dont think it's really all that likely/common for a screenshot to be that large in the first place)