Add auto-start targets feature with dashboard section

- Add auto_start boolean field to PictureTarget model (persisted per-target)
- Wire auto_start through API schemas, routes, and store
- Auto-start targets on server boot in main.py lifespan
- Add star toggle button on target cards (next to delete button)
- Add auto-start section on dashboard between performance and profiles
- Remove auto-start section from profiles tab

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/wled_controller/static/css/cards.css

@@ -103,6 +103,30 @@ section {
     position: static;
 }
 
+.card-autostart-btn {
+    background: none;
+    border: none;
+    color: #777;
+    font-size: 1rem;
+    width: 28px;
+    height: 28px;
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    cursor: pointer;
+    border-radius: 4px;
+    transition: color 0.2s, background 0.2s;
+}
+
+.card-autostart-btn:hover {
+    color: var(--warning-color, #ffc107);
+    background: rgba(255, 193, 7, 0.1);
+}
+
+.card-autostart-btn.active {
+    color: var(--warning-color, #ffc107);
+}
+
 .card-power-btn {
     background: none;
     border: none;