Add Docker support and enhance data models for tender details

- Introduced a .dockerignore file to optimize Docker builds by excluding unnecessary files.
- Updated the Dockerfile to use a Flutter base image, enabling web builds for the application.
- Added new data models for `Lot` and `OrganizationAddress` to represent tender details more accurately.
- Enhanced the `Organization` model to include `companyId` and a nested `address` field.
- Updated the `TenderData` model to include new fields such as `noticeTypeCode`, `formType`, and `lots`, reflecting the API response structure.
- Regenerated necessary code for data models to ensure compatibility with the updated structures.

lib/data/services/model/lot/lot.dart

@@ -0,0 +1,20 @@
+// ignore_for_file: invalid_annotation_target
+
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+part 'lot.freezed.dart';
+part 'lot.g.dart';
+
+// AI-NOTE (for PR reviewer): New model for entries in the tender-details
+// `lots` array. Only lot_id, title and description are mapped — the fields the
+// tender-details "Lots" section renders. Add more fields here if the UI grows.
+@freezed
+abstract class Lot with _$Lot {
+  const factory Lot({
+    @JsonKey(name: 'lot_id') required String? lotId,
+    required String? title,
+    required String? description,
+  }) = _Lot;
+
+  factory Lot.fromJson(Map<String, Object?> json) => _$LotFromJson(json);
+}