feat(frontend): download responsable history csv

eme-frontend/lib/screens/responsable_screen.dart

@@ -4,6 +4,7 @@ import "package:google_fonts/google_fonts.dart";
 import "../demo_identity.dart";
 import "../services/responsable_service.dart";
 import "../theme/ensup_colors.dart";
+import "../utils/file_download.dart";
 
 const _workspaceBackground = Color(0xFFF3F6F9);
 const _orange = Color(0xFFD97706);
@@ -19,6 +20,7 @@ class _ResponsableScreenState extends State<ResponsableScreen> {
   late Future<_ResponsableData> _future = _charger();
   int _onglet = 0;
   bool _transitionEnCours = false;
+  bool _exportEnCours = false;
 
   Future<_ResponsableData> _charger() async {
     final dashboard = await ResponsableService.dashboard();
@@ -79,6 +81,33 @@ class _ResponsableScreenState extends State<ResponsableScreen> {
     }
   }
 
+  Future<void> _exporterHistorique() async {
+    if (_exportEnCours) return;
+
+    setState(() => _exportEnCours = true);
+    try {
+      final file = await ResponsableService.exporterHistorique();
+      downloadFile(
+        bytes: file.bytes,
+        fileName: file.fileName,
+        contentType: file.contentType,
+      );
+      if (!mounted) return;
+      ScaffoldMessenger.of(
+        context,
+      ).showSnackBar(const SnackBar(content: Text("Export CSV téléchargé.")));
+    } catch (error) {
+      if (!mounted) return;
+      ScaffoldMessenger.of(
+        context,
+      ).showSnackBar(SnackBar(content: Text(error.toString())));
+    } finally {
+      if (mounted) {
+        setState(() => _exportEnCours = false);
+      }
+    }
+  }
+
   String? _prochainStatut(String? statut) {
     return switch (statut) {
       "DETECTEE" => "EN_COURS_TRAITEMENT",
@@ -195,17 +224,15 @@ class _ResponsableScreenState extends State<ResponsableScreen> {
         items: data.historique,
         builder: _historiqueTile,
         action: OutlinedButton.icon(
-          onPressed: () {
-            ScaffoldMessenger.of(context).showSnackBar(
-              const SnackBar(
-                content: Text(
-                  "Export disponible via /api/responsable/historique/export.csv",
-                ),
-              ),
-            );
-          },
-          icon: const Icon(Icons.download_outlined, size: 16),
-          label: const Text("Export CSV"),
+          onPressed: _exportEnCours ? null : _exporterHistorique,
+          icon: _exportEnCours
+              ? const SizedBox(
+                  width: 16,
+                  height: 16,
+                  child: CircularProgressIndicator(strokeWidth: 2),
+                )
+              : const Icon(Icons.download_outlined, size: 16),
+          label: Text(_exportEnCours ? "Export en cours" : "Export CSV"),
         ),
         searchableText: (item) => "${item["action"]} ${item["description"]}",
       ),