feat: Add satellite imagery with Map/Satellite/Hybrid view modes

- Add viewMode state to store with localStorage persistence
- Add satellite layer functions to MapView (ESRI World Imagery via nginx proxy)
- Add view mode segmented control in LayerControl popover
- Add view-mode-control CSS styles
- Hide/show vector fills and lines based on view mode

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

src/index.css

@@ -314,6 +314,39 @@ body {
   box-shadow: var(--shadow-lg);
 }
 
+.view-mode-control {
+  display: flex;
+  gap: 2px;
+  padding: 8px;
+  border-bottom: 1px solid var(--border-subtle);
+}
+
+.view-mode-btn {
+  flex: 1;
+  display: flex;
+  flex-direction: column;
+  align-items: center;
+  gap: 2px;
+  padding: 6px 8px;
+  border: none;
+  border-radius: 6px;
+  background: transparent;
+  color: var(--text-secondary);
+  font-size: var(--text-xs);
+  cursor: pointer;
+  transition: all 0.15s;
+}
+
+.view-mode-btn:hover {
+  background: var(--bg-overlay);
+  color: var(--text-primary);
+}
+
+.view-mode-btn.active {
+  background: var(--accent);
+  color: var(--text-inverse);
+}
+
 .layer-control-header {
   padding: 4px 12px 6px;
   font-size: var(--text-xs);