feat(Fundamentals): add fundamentals service

FinlyticFundamentals/Entities/FundamentalsSettingsEntity.cs

@@ -0,0 +1,14 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+
+namespace FinlyticFundamentals.Entities;
+
+public class FundamentalsSettingsEntity
+{
+    [Key]
+    public Guid Id { get; set; }
+
+    public int CacheTtlHours { get; set; } = 24;
+    public bool EnableYahooFallback { get; set; } = true;
+    public DateTime UpdatedAt { get; set; } = DateTime.UtcNow;
+}