Fixes #14931.

Preserve host and non-default port from Host / :authority when constructing Vite HTTPS/HTTP2 requests in @cloudflare/vite-plugin.

Under HTTPS, Vite uses HTTP/2. Pseudo-headers like :authority are skipped when building Fetch headers, so Host can be missing and host resolution falls back to localhost without :5173. Auth libraries like Clerk then build handshake redirect_url / X-Forwarded-Host from that broken origin and loop.

This change:

• Resolves host from req.headers.host then :authority
• Passes it into createRequest as options.host
• Sets Host when missing so existing X-Forwarded-Host logic keeps e.g. localhost:5173

Validated locally with an equivalent pnpm patch against @cloudflare/vite-plugin@1.45.1 (Clerk handshake no longer drops :5173 port under HTTPS).

Related: #8684 / #8706, #10884, #13801 / #13920

• Tests
  • Tests included/updated
  • Manual testing has been completed as follows:
    • Vite server.https (mkcert) + --host
    • Open https://localhost:5173 with Clerk middleware
    • Confirm handshake Location / redirect_url keeps :5173 (no redirect loop to https://localhost/)
    • Confirm HTTP http://localhost:5173 still works
• Public documentation
  • Documentation not necessary because: bug fix restoring correct request origin/port behavior; no new public API