Sprint 18: Notification Center, Routen entdecken, Onboarding, Admin-Erweiterungen

- Notifications: History-Tabelle, /api/notifications Endpoints, push.py schreibt in DB
- Notifications: Page (notifications.js) mit Badge, Typen-Icons, gelesen-Markierung
- Routen: Entdecken-Modus mit Ersteller-Anzeige, Nearby-Filter, Mine/Discover Toggle
- Onboarding: Willkommens-Modal nach Registrierung, Push-Angebot nach Login
- Admin: Scheduler-Tab (Jobs anzeigen + manuell triggern), System-Health (DB/Disk/Uptime)
- Admin: Audit-Log (wer hat was wann gemacht), erweiterte Stats (Push-Abos, aktive User, Routen)
- SW: by-v152, APP_VER 125

backend/static/css/components.css

@@ -1827,6 +1827,42 @@ textarea.form-control {
   gap:         var(--space-2);
 }
 .rk-card-author { font-size: var(--text-xs); color: var(--c-text-muted); }
+.rk-card-creator {
+  display:       flex;
+  align-items:   center;
+  gap:           4px;
+  font-size:     var(--text-xs);
+  font-weight:   600;
+  color:         var(--c-primary);
+  margin-bottom: 2px;
+}
+/* Mode-Toggle: Meine Routen / Entdecken */
+.rk-mode-toggle {
+  display:       flex;
+  gap:           0;
+  margin-bottom: var(--space-3);
+  border:        1px solid var(--c-border);
+  border-radius: var(--radius-lg);
+  overflow:      hidden;
+  align-self:    flex-start;
+}
+.rk-mode-btn {
+  flex:          1;
+  padding:       6px 16px;
+  font-size:     var(--text-sm);
+  font-weight:   500;
+  background:    var(--c-bg);
+  color:         var(--c-text-secondary);
+  border:        none;
+  cursor:        pointer;
+  transition:    background 0.15s, color 0.15s;
+  white-space:   nowrap;
+}
+.rk-mode-btn.active {
+  background: var(--c-primary);
+  color:      #fff;
+}
+.rk-mode-btn:first-child { border-right: 1px solid var(--c-border); }
 .rk-dl-btn {
   font-size:     var(--text-xs);
   padding:       4px 8px;