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.css

@@ -416,57 +416,6 @@ button.danger:hover:not(:disabled) {
 .modal-type-label { display: block; }
 .modal-actions { display: flex; justify-content: flex-end; gap: 10px; margin-top: 2px; }
 
-/* -------- Animated neon edge glow (beam travels around the border) --------
-   A rotating conic-gradient (transform: rotate — works on iOS Safari, unlike
-   an @property-animated gradient angle) clipped to a thin border ring. The
-   glow halo is a drop-shadow on the parent so it survives the child's mask. */
-#edge-glow {
-  position: fixed;
-  inset: 0;
-  z-index: 9998;
-  pointer-events: none;
-  filter: drop-shadow(0 0 6px var(--neon)) drop-shadow(0 0 16px var(--cyan));
-}
-#edge-glow .beam {
-  position: absolute;
-  inset: 0;
-  padding: 3px;                 /* thickness of the glowing border band */
-  overflow: hidden;
-  /* Keep only the padding ring (border band); punch out the interior. */
-  -webkit-mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
-  -webkit-mask-composite: xor;
-          mask: linear-gradient(#000 0 0) content-box, linear-gradient(#000 0 0);
-          mask-composite: exclude;
-}
-#edge-glow .beam::before {
-  content: "";
-  position: absolute;
-  top: 50%;
-  left: 50%;
-  width: 200vmax;               /* > viewport diagonal at any rotation */
-  height: 200vmax;
-  transform: translate(-50%, -50%);
-  background: conic-gradient(
-    from 0deg,
-    transparent 0deg,
-    transparent 40deg,
-    var(--cyan) 66deg,
-    #ffffff 90deg,
-    var(--neon) 114deg,
-    transparent 140deg,
-    transparent 360deg
-  );
-  animation: beamspin 7s linear infinite;
-  will-change: transform;
-}
-@keyframes beamspin {
-  from { transform: translate(-50%, -50%) rotate(0deg); }
-  to   { transform: translate(-50%, -50%) rotate(360deg); }
-}
-@media (prefers-reduced-motion: reduce) {
-  #edge-glow .beam::before { animation: none; }
-}
-
 /* -------- Top tabs -------- */
 .tabs { display: flex; gap: 4px; margin-left: 18px; align-self: stretch; align-items: flex-end; }
 .tabs .tab {