tazel.tala.run only redirects to tazel.net now. The product list and the
Tazel plugin catalog link the new address directly.

Give every page a Content-Security-Policy with its own nonce

The pages of progmasoft.com and its hosts had no content security
policy. The proxy now creates a 128-bit nonce for every request and sends
the policy both ways: on the request, so that Next marks its own inline
scripts with the nonce, and on the response. The layout reads the nonce
for the theme bootstrap. Every page is rendered on demand already, so
none is served with a stale nonce.

Scripts may come from the host, carry the nonce, or be Cloudflare's Web
Analytics beacon from static.cloudflareinsights.com, which reports to
cloudflareinsights.com. 'strict-dynamic' is left out, because browsers
ignore host sources under it and the beacon is added by Cloudflare
without a nonce. Styles allow inline ones; objects, framing and other
base URLs are refused. There is no form-action: sign-in and OAuth
consent end in redirects to other hosts, loopback addresses included,
and browsers apply form-action to them. The development server also
gets 'unsafe-eval' for its hot reload.

Tests check the nonce and each directive; ARCHITECTURE.md describes the
policy.

Accept plugin versions of up to five numbers

Tazel takes A.B.C, then .D, .E and -METADATA if needed, so the descriptor
check follows it.

Accept plugin versions of four numbers

Progmasoft's releases move to four numbers, and the plugins publish here.

Serve the Progmasoft mark as the site icon

The sites declared no icon and /favicon.ico answered 404, so search
engines and assistants that show a site's icon (DuckDuckGo, ChatGPT)
fell back to a gray placeholder; the only copy of the mark was the BIMI
logo for mail.

The app now has the Next.js icon files, so every page links them:

- app/icon.svg: the four squares of the BIMI logo, cropped to the mark
  so it fills a browser tab, on a transparent field.
- app/favicon.ico: the same mark at 16, 32 and 48 pixels (PNG entries),
  for clients that ask for /favicon.ico without reading the page.
- app/apple-icon.png: 180 pixels on the white field of the BIMI logo,
  since iOS fills transparency with black.

The proxy rewrites paths per host, which would send /icon.svg on the
account, ViGet and the other hosts into their own page trees; the
matcher now skips the two new files as it already skipped favicon.ico,
so every Progmasoft host serves the same icons.

Provision the reserved accounts on the server