feat(docs): add analytics and mcp version widget

[JSONbored]

Summary

• add an env-gated Umami analytics integration for the VitePress docs
• add a dark-only MCP version widget that reads the latest npm package version client-side
• add docs build smoke coverage so analytics and package-version behavior are checked in CI

What changed

• added McpVersionPill to the VitePress nav/footer slots
• wired optional Umami script generation through GITTENSORY_UMAMI_SCRIPT_URL, GITTENSORY_UMAMI_WEBSITE_ID, and GITTENSORY_UMAMI_DOMAINS
• passed the analytics repo variables into the Pages workflow
• updated privacy docs to describe docs analytics separately from MCP/API privacy
• added docs:smoke and included it in test:ci

Why

• the docs site should show the current public MCP package version without requiring a docs rebuild
• analytics should be explicit, privacy-preserving, and absent unless configured
• Pages remains the only docs deployment path

Validation

• npm run changelog:check
• git diff --check
• npm run test:ci
• docs smoke with fake Umami environment variables

Notes

• this does not publish a new MCP package
• Umami will only appear on the built site after the repository variables are configured
• GitHub Pages remains the docs deployment target; no Cloudflare Worker deployment is added