Fix certificate View link (wrong /study/certificate URL), certificates in My Account, name on certificate; v2.10.10

- Certificate URLs in the account overview and the issuance email pointed at /study/certificate/:token,
  which the router treated as a lesson page; now /certificate/:token (old links redirect)
- My Account Certificates card lists every enrolled study: progress, Generate, View, Copy link, Download PNG, Share
- Certificate canvas used a non-existent /api/study-account route and always printed 'Student'; now reads the account name
- Panel no longer collapses after generating

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

src/App.css

@@ -4488,6 +4488,59 @@
   .account-stats { grid-template-columns: repeat(2, minmax(0, 1fr)); }
 }
 
+.account-chip--muted { color: var(--brand-muted); border-color: rgba(255, 255, 255, 0.16); background: rgba(255, 255, 255, 0.04); }
+
+.account-cert-study {
+  border-top: 1px solid rgba(201, 168, 76, 0.12);
+  padding: 0.35rem 0 0.6rem;
+}
+
+.account-cert-study:first-of-type { border-top: none; }
+
+.account-cert-study > summary {
+  display: flex;
+  align-items: center;
+  justify-content: space-between;
+  flex-wrap: wrap;
+  gap: 0.6rem;
+  padding: 0.55rem 0;
+  list-style: none;
+  cursor: pointer;
+}
+
+.account-cert-study > summary::-webkit-details-marker { display: none; }
+
+.account-cert-study > summary::after {
+  content: '▾';
+  color: var(--brand-gold);
+  margin-left: auto;
+  transition: transform 0.15s ease;
+}
+
+.account-cert-study:not([open]) > summary::after { transform: rotate(-90deg); }
+
+.account-cert-title {
+  color: var(--brand-warm-white);
+  font-weight: 600;
+}
+
+.account-cert-study .account-cert-actions {
+  display: flex;
+  gap: 0.6rem;
+  flex-wrap: wrap;
+  margin: 0.25rem 0 0.75rem;
+}
+
+.account-cert-study .account-cert-actions .btn-primary,
+.account-cert-study .account-cert-actions .btn-secondary {
+  font-size: 0.82rem;
+  padding: 0.5rem 1.1rem;
+}
+
+.account-cert-study .study-cert-panel { margin-top: 0.5rem; }
+.account-cert-study .study-cert-heading { display: none; }
+.account-cert-study .study-cert-canvas { width: 100%; height: auto; max-width: 100%; }
+
 /* ── Study hub (guest landing) ── */
 .study-hub-count {
   margin: 1.25rem 0 0;