docs: a README with a face, in English and Portuguese; decode every HTML entity in previews

The README opens like a product page: the mark, a line on what it is, the
links, the language switch and a picture of the real interface running on an
invented mailbox, in dark and light and in both languages. scripts/screenshots
holds that invented mailbox and the script that photographs it, so the pictures
can be redone. Previews now decode any HTML entity through the browser rather
than a short list, so a Portuguese or marketing preview no longer prints
ç or ·.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

scripts/screenshots/README.md

@@ -0,0 +1,25 @@
+# Photographing the interface
+
+`stub-server.mjs` stands in for the auth and protocols services and serves a
+small mailbox that is entirely invented (names, addresses on reserved example
+domains, messages). It exists so the webmail can be run, worked on and
+photographed without a mail server or anyone's real mail.
+
+    node scripts/screenshots/stub-server.mjs      # listens on :4001
+    cd services/webmail
+    AUTH_SERVICE_URL=http://127.0.0.1:4001 \
+    PROTOCOLS_SERVICE_URL=http://127.0.0.1:4001 npx next dev -p 3100
+
+Open `http://localhost:3100/user/mail/inbox` with a cookie named
+`lm_user_session` holding any token with the claims the middleware reads (the
+capture script builds one).
+
+`capture.mjs` writes the pictures the README uses into `docs/img/`, in English
+and Portuguese, dark and light:
+
+    cd scripts/screenshots && npm install --no-save puppeteer-core
+    CHROME_PATH=/path/to/chrome node capture.mjs
+
+It needs a Chrome, and the webmail running as above. The stub keeps its state in
+memory (opening a message marks it read); the script resets it before every
+picture through `/__reset`, so each one starts from the same mailbox.