Flutter: fitur Tambah Saham (tab Saham + form kode/perusahaan/sektor)

- Tab baru 'Saham' di NavigationBar (daftar master saham dari saat.saham)
- FAB konteks: di tab Saham buka form Tambah Saham, di tab lain catat transaksi
- EditSahamScreen: form tambah saham baru (kode ticker, perusahaan, sektor)
- StockService: method addSaham(), updateSaham(), hapusSaham() ke Odoo

flutter/lib/services/stock_service.dart

@@ -15,6 +15,35 @@ class StockService {
     return (res as List).map((e) => Saham.fromOdoo(e as Map<String, dynamic>)).toList();
   }
 
+  // Tambah saham baru ke Odoo saat.saham.create
+  Future<int> addSaham({
+    required String kode,
+    String? perusahaan,
+    String? sektor,
+  }) async {
+    final vals = <String, dynamic>{
+      'name': kode,
+      if (perusahaan != null && perusahaan.isNotEmpty) 'perusahaan': perusahaan,
+      if (sektor != null && sektor.isNotEmpty) 'sector': sektor,
+    };
+    final res = await client.executeKwd('saat.saham', 'create', args: [vals]);
+    return (res as num).toInt();
+  }
+
+  // Update data saham (perusahaan, sektor)
+  Future<void> updateSaham(int id, {String? perusahaan, String? sektor}) async {
+    final vals = <String, dynamic>{
+      if (perusahaan != null) 'perusahaan': perusahaan,
+      if (sektor != null) 'sector': sektor,
+    };
+    await client.executeKwd('saat.saham', 'write', args: [[id], vals]);
+  }
+
+  // --- Hapus saham (optional) ---
+  Future<void> hapusSaham(int id) async {
+    await client.executeKwd('saat.saham', 'unlink', args: [[id]]);
+  }
+
   // ---- Portofolio ----
   Future<List<Portfolio>> listPortofolio() async {
     final fields = [