v0.28.1 — re-vendored landing page and browser client

Vendored-asset-only release: the landing page (vgi/http/landing.html) and the browser client bundle (vgi/http/vgi-client.js) are re-vendored from the same builds vgi-rpc-typescript publishes, kept byte-identical across the repos. No Python code changed.

• The client bundle honors X-VGI-Content-Encoding. The previous copy decoded zstd only and ignored the custom header, which broke the landing page on any worker behind Cloudflare — workerd stamps X-VGI-Content-Encoding: gzip on every response, because the edge re-gzips a standard Content-Encoding and workerd has no zstd encoder. Python-hosted workers were never affected: there the browser's own Accept-Encoding wins, the server stamps a standard Content-Encoding, and fetch decodes it transparently.
• Long function signatures wrap inside their card instead of overflowing it, and the summary line shows argument types.
• Macros get their own groups instead of being counted and displayed as scalar/table functions, and their untyped parameters no longer show a fabricated ANY.