Fix coverage: add /api/coverage route, remove stray gather code from loadCoverage

scripts/check_node29.py

@@ -0,0 +1,22 @@
+import json
+
+data = json.load(open(r'F:\seismic_webapp\data\index.json'))
+
+node29 = data['nodes'].get('29')
+if node29:
+    print(f"Node 29:")
+    print(f"  Position: {node29.get('position')}")
+    print(f"  Dates disponibles: {list(node29.get('dates', {}).keys())}")
+    for date, files in node29.get('dates', {}).items():
+        print(f"  {date}: {len(files)} fichiers")
+        for f in files[:2]:
+            print(f"    - {f['path']}")
+else:
+    print("Node 29 non trouvé dans l'index")
+
+print("\n--- Tous les nodes avec données ---")
+for node_id, node in data['nodes'].items():
+    if node.get('dates') and len(node['dates']) > 0:
+        has_pos = node.get('position') is not None
+        dates = list(node['dates'].keys())
+        print(f"Node {node_id}: pos={has_pos}, dates={dates}")