feat: Implement agent filtering by integrating a new API endpoint for filterable fields, introducing filter data models, and adding a dedicated filter sheet UI, alongside an updated profile icon.

lib/features/agents/data/models/filterable_field.dart

@@ -0,0 +1,39 @@
+class FilterOption {
+  final String value;
+  final String label;
+
+  const FilterOption({required this.value, required this.label});
+
+  factory FilterOption.fromJson(Map<String, dynamic> json) {
+    return FilterOption(
+      value: json['value'] as String? ?? '',
+      label: json['label'] as String? ?? '',
+    );
+  }
+}
+
+class FilterableField {
+  final String slug;
+  final String name;
+  final String fieldType;
+  final List<FilterOption> options;
+
+  const FilterableField({
+    required this.slug,
+    required this.name,
+    required this.fieldType,
+    this.options = const [],
+  });
+
+  factory FilterableField.fromJson(Map<String, dynamic> json) {
+    return FilterableField(
+      slug: json['slug'] as String? ?? '',
+      name: json['name'] as String? ?? '',
+      fieldType: json['fieldType'] as String? ?? '',
+      options: (json['options'] as List<dynamic>?)
+              ?.map((e) => FilterOption.fromJson(e as Map<String, dynamic>))
+              .toList() ??
+          const [],
+    );
+  }
+}