feat: package and smoke test Chromium extension

[WangEn]

What changed

• move the canonical Cloudflare Worker/D1 configuration to root wrangler.jsonc
• point the Web Cloudflare Vite plugin at the root Wrangler config so the repository can be deployed as one Worker + Static Assets + D1 unit
• add a Deploy to Cloudflare button and document Workers Git integration / CLI deployment
• prepare the Chromium extension as version 0.1.0 and add WXT ZIP packaging
• add a versioned Browser Bridge capability handshake (protocolVersion: 1 + explicit capability flags)
• reject incompatible Web/Extension bridge protocol versions and fall back to Web-only behavior
• add a real Playwright Chromium smoke script that loads the unpacked MV3 extension and verifies service worker startup, capability handshake, open-tab enumeration/activation, and pinned Session restore
• extend CI with a Chromium extension job and upload the packaged ZIP as an artifact
• add a tag-driven GitHub Release workflow for extension ZIPs
• document the post-deploy live bridge permission smoke checklist

Why Workers rather than Pages

Dockmark is now a React SPA + Worker API + D1 application. Cloudflare Workers Static Assets deploys the Worker and static assets as one unit, while the root Wrangler config lets Deploy to Cloudflare provision/bind D1. Pages remains usable as a static platform but would split the current application model unnecessarily.

Browser test boundary

CI does not bypass Chromium's optional host-permission prompt. The automated smoke test exercises the real packaged extension and privileged browser APIs. The README documents the short post-deployment check that confirms the user-granted Web bridge on the real workers.dev or custom origin.