Public demo / playground site with live config editor

[PAMulligan]

Summary

Stand up a dedicated demo site (separate from pmds.info) where prospective adopters can tweak the widget's config in real time and copy a ready-made embed snippet.

Motivation

The README points to pmds.info as the demo, but that site is a small-business sales page, not a product playground. A dedicated demo with knobs for every prop converts trial users much faster.

Acceptance Criteria

• New examples/playground app deployed to a claudius.dev or *.pages.dev subdomain
• Controls for every public prop: title, subtitle, theme, accentColor, position, welcomeMessage, persistMessages, proactive trigger config
• Live preview pane + generated embed snippet with copy-to-clipboard
• Mobile and desktop viewport toggles
• "Open in CodeSandbox/StackBlitz" button for each preset
• Linked from README, docs site, and the Chrome Web Store-equivalent listings