fix(site): prevent mobile evidence overflow

[LauraGPT]

Summary

• allow long evidence labels such as pinned SHA-256 values to wrap inside their grid track
• give evidence list items a zero minimum width so one unbroken token cannot widen the page
• add mobile and desktop Playwright coverage for the audio.cpp deployment page

Root cause

The new pinned SenseVoice GGUF evidence label contains a 64-character SHA-256. The evidence grid item retained its intrinsic minimum width, so the mobile document expanded from a 375 px client width to a 628 px scroll width. Command blocks already scroll internally and were not the document-level cause.

Validation

• reproduced before the fix at a 390 x 844 viewport: clientWidth=375, scrollWidth=628
• after the fix at 390 x 844: clientWidth=375, scrollWidth=375; all five evidence items have scrollWidth == clientWidth
• after the fix at 1440 x 900: no horizontal overflow and the evidence grid remains three columns
• all 14 audio.cpp command blocks stay within their parent width on mobile
• python3 -m pytest web-pages/product-site/tests -q (68 passed)
• generated 25 product pages and validated 100 HTML pages

The added Playwright cases run both mobile and desktop layouts in CI and save full-page screenshots.