Remove edge glow; prefill MCMS URL from env; drop self-signed-cert option

- Remove the animated neon edge-glow entirely (HTML element + CSS) — it
  couldn't be made to follow the border reliably on iOS Safari.
- Add PFW_MCMS_URL: the web server prefills the login "Host URL" field with
  it (injected as the input's value in the served index; still editable).
  Documented in env.example + web README.
- Remove the "Accept self-signed TLS certificate" option: the checkbox is
  gone and both backends now always use rejectUnauthorized:true — MCMS must
  present a valid certificate. Dropped the acceptSelfSigned plumbing from the
  renderer and both login handlers.

Docs: CLAUDE.md (drop edge-glow section, update login note) + web README.

Verified: node --check; no stale refs (in-self-signed / acceptSelfSigned /
edge-glow / beamspin); served index carries value="…" only when
PFW_MCMS_URL is set, and no self-signed checkbox.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

renderer/app.js

@@ -223,14 +223,13 @@ $('#btn-login').addEventListener('click', async () => {
   const baseUrl = $('#in-host').value.trim();
   const username = $('#in-user').value.trim();
   const password = $('#in-pass').value;
-  const acceptSelfSigned = $('#in-self-signed').checked;
   if (!baseUrl || !username || !password) {
     $('#login-error').textContent = 'Host, username and password are required.';
     return;
   }
   $('#btn-login').disabled = true;
   $('#btn-login').textContent = 'Connecting…';
-  const res = await window.api.login({ baseUrl, username, password, acceptSelfSigned });
+  const res = await window.api.login({ baseUrl, username, password });
   $('#btn-login').disabled = false;
   $('#btn-login').textContent = 'Connect';
   if (!res.ok) {