Dissolve System Settings into individual settings pages

The monolithic tab page competed with the settings rail as a second
navigation system, and its Integrations tab was a dumping ground. Each
section is now its own routed rail page (ServiceNow, Zabbix Supplies,
Dell Warranty, Collector PC Types, Branding, Floor Map, Printing and
Labels, Email/SMTP, Audit, Authentication, Asset Identifiers, Global
Search), thin over a shared useSystemSettings composable, grouped
logically in the rail with system groups clustered last. Old
/settings/system?tab= URLs redirect to the right page.

Also fixes the post-login redirect: the auth guard now remembers the
intended destination and Login returns there (same-site paths only).

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

frontend/src/assets/style.css

@@ -1083,6 +1083,212 @@ td.actions {
   border-bottom: 1px solid var(--border);
 }
 
+/* Settings form controls - shared by the individual settings pages
+   (branding, printing, email, integrations, identifiers, search, map...). */
+.setting-group {
+  border-top: 1px solid var(--border);
+  padding-top: 1rem;
+}
+.setting-group:first-of-type {
+  border-top: none;
+  padding-top: 0;
+}
+.setting-group h3 {
+  margin: 0 0 0.5rem 0;
+  font-size: 1rem;
+  color: var(--text);
+}
+.setting-description {
+  color: var(--text-light);
+  font-size: 0.9rem;
+  margin: 0 0 1rem 0;
+  line-height: 1.5;
+}
+.settings-grid {
+  display: grid;
+  grid-template-columns: repeat(auto-fit, minmax(180px, 1fr));
+  gap: 1rem;
+  margin-bottom: 1rem;
+}
+.setting-row {
+  margin-bottom: 1rem;
+}
+.setting-row.full-width {
+  grid-column: 1 / -1;
+}
+.setting-row label {
+  display: flex;
+  flex-direction: column;
+  gap: 0.5rem;
+}
+.setting-row label span {
+  color: var(--text);
+  font-size: 0.9rem;
+}
+.setting-row input,
+.setting-row select {
+  padding: 0.5rem;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: var(--bg);
+  color: var(--text);
+  font-size: 1rem;
+  max-width: 400px;
+}
+.setting-row input[type="number"] {
+  max-width: 120px;
+}
+.setting-row input:focus,
+.setting-row select:focus {
+  outline: none;
+  border-color: var(--primary);
+}
+.input-hint {
+  color: var(--text-light);
+  font-size: 0.8rem;
+}
+.toggle-label {
+  flex-direction: row !important;
+  align-items: center;
+  justify-content: space-between;
+  max-width: 400px;
+}
+.toggle-hint {
+  display: block;
+  margin-top: -0.5rem;
+  margin-left: 0;
+}
+.toggle-btn {
+  position: relative;
+  width: 50px;
+  height: 26px;
+  border-radius: 13px;
+  border: none;
+  background: var(--secondary);
+  cursor: pointer;
+  transition: background 0.2s;
+}
+.toggle-btn.active {
+  background: var(--success);
+}
+.toggle-slider {
+  position: absolute;
+  top: 3px;
+  left: 3px;
+  width: 20px;
+  height: 20px;
+  border-radius: 50%;
+  background: white;
+  transition: transform 0.2s;
+}
+.toggle-btn.active .toggle-slider {
+  transform: translateX(24px);
+}
+.status-indicator {
+  display: flex;
+  align-items: center;
+  gap: 0.5rem;
+  padding: 0.75rem;
+  background: var(--bg);
+  border-radius: 4px;
+  font-size: 0.9rem;
+  color: var(--text-light);
+  max-width: 400px;
+  margin-bottom: 1rem;
+}
+.status-dot {
+  width: 10px;
+  height: 10px;
+  border-radius: 50%;
+  flex-shrink: 0;
+}
+.status-dot.inactive { background: var(--secondary); }
+.status-dot.warning { background: var(--warning); }
+.status-dot.pending { background: var(--primary); }
+.status-dot.success { background: var(--success); }
+.test-btn {
+  padding: 0.5rem 1rem;
+  background: var(--primary);
+  color: white;
+  border: none;
+  border-radius: 4px;
+  cursor: pointer;
+  font-size: 0.9rem;
+}
+.test-btn:hover:not(:disabled) {
+  background: var(--primary-dark);
+}
+.test-btn:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+.view-logs-link {
+  display: inline-block;
+  margin-top: 0.5rem;
+  color: var(--link);
+  text-decoration: none;
+  font-size: 0.9rem;
+}
+.view-logs-link:hover {
+  text-decoration: underline;
+}
+.identifier-matrix {
+  width: 100%;
+  border-collapse: collapse;
+}
+.identifier-matrix th,
+.identifier-matrix td {
+  padding: 0.6rem 0.75rem;
+  text-align: center;
+  border-bottom: 1px solid var(--border);
+}
+.identifier-matrix th:first-child,
+.identifier-matrix td.identifier-name {
+  text-align: left;
+}
+.identifier-matrix th {
+  color: var(--text-light);
+  font-weight: 600;
+  font-size: 0.9rem;
+}
+.identifier-matrix .identifier-name {
+  color: var(--text);
+}
+.color-input-row {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+}
+.color-input-row input[type="color"] {
+  width: 48px;
+  height: 34px;
+  padding: 2px;
+  cursor: pointer;
+}
+.color-input-row input[type="text"] {
+  max-width: 160px;
+}
+.map-upload-row {
+  display: flex;
+  align-items: center;
+  gap: 0.75rem;
+  margin-top: 0.4rem;
+}
+.map-thumb {
+  height: 40px;
+  border: 1px solid var(--border);
+  border-radius: 4px;
+  background: #fff;
+}
+.map-thumb-dark { background: #222; }
+.settings-success {
+  margin-top: 1rem;
+  padding: 0.75rem;
+  background: var(--success);
+  color: white;
+  border-radius: 4px;
+}
+
 /* Info List */
 .info-list {
   display: flex;