separate account settings from shop settings

- Create dedicated /admin/account page for user account management
- Move email, password, and 2FA settings from /admin/settings
- Add Account link to top of admin sidebar navigation
- Add TOTP-based two-factor authentication with NimbleTOTP
- Add TOTP verification LiveView for login flow
- Add AccountController for TOTP session management
- Remove Advanced section from settings (duplicated in dev tools)
- Remove user email from sidebar footer (replaced by Account link)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

assets/css/admin/components.css

@@ -1208,6 +1208,105 @@
   overflow-x: auto;
 }
 
+.admin-info-box .admin-btn-primary {
+  color: var(--t-text-inverse);
+}
+
+/* ── TOTP / 2FA ── */
+
+.admin-totp-setup {
+  display: flex;
+  flex-direction: column;
+  gap: 1.25rem;
+  align-items: center;
+  text-align: center;
+}
+
+.admin-totp-qr {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 0.5rem;
+}
+
+.admin-qr-code {
+  padding: 1rem;
+  background: white;
+  border-radius: 0.5rem;
+  box-shadow: 0 1px 3px rgb(0 0 0 / 0.1);
+}
+
+.admin-qr-code svg {
+  display: block;
+  width: 180px;
+  height: 180px;
+}
+
+.admin-totp-divider {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  width: 100%;
+  color: var(--admin-text-muted);
+  font-size: 0.8125rem;
+
+  &::before,
+  &::after {
+    content: "";
+    flex: 1;
+    height: 1px;
+    background: var(--admin-border);
+  }
+}
+
+.admin-totp-copy {
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 0.5rem;
+  width: 100%;
+}
+
+.admin-copy-field {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  padding: 0.5rem;
+  background: var(--admin-bg-secondary);
+  border-radius: 0.375rem;
+  max-width: 100%;
+}
+
+.admin-copy-field code {
+  font-size: 0.8125rem;
+  word-break: break-all;
+}
+
+.admin-backup-codes {
+  display: grid;
+  grid-template-columns: repeat(2, 1fr);
+  gap: 0.5rem;
+  margin-top: 1rem;
+}
+
+.admin-backup-code {
+  padding: 0.375rem 0.75rem;
+  background: white;
+  border-radius: 0.25rem;
+  font-family: ui-monospace, monospace;
+  font-size: 0.875rem;
+  text-align: center;
+  letter-spacing: 0.05em;
+}
+
+.admin-dl-compact {
+  font-size: 0.8125rem;
+}
+
+.admin-dl-compact .admin-dl-row {
+  padding-block: 0.25rem;
+}
+
 /* ── Link variants ── */
 
 .admin-link-danger {